I've been having the same issues as other with 5DIV reporting Error 70. This issue also plagues the Canon 1DXii with the Sigma Art24mm and either SanDisk 64gb Cfast 2.0 or Lexar 3500x 256gb CFast 2.0.   Answers to the questions DJI admins are about to ask:
1. The camera was triggered in Video mode, and begins producing "Error 70" in which the camera is entirely responsive to anything but pulling the battery.
2. The cfast cards are formatted in camera. Cards can surely be formatted in a computer, but of course a card needs to be formated in camera prior to use.

Thanks for the upcoming and hopefuly resolution.  Touching the camera is not ideal.

I get the same problem. Don't think its a lens issue. I am using a 1DX2 and a 16-35 F4 IS L

Hi there, we see you have posted in another thread and Susan has replied, our engineers are working with Canon to handle the SDK compatibility issues furtherly. It takes some time to optimize and test the compatibility, we'll try to figure this out through the firmware upgrade. Please also pay attention to the official website update announcement, thank you for your support.

Currently, you may refer the below to fix this temporarily. Sorry for this.
1. Set the power switch to and then turn the camera on again
2. Remove and install the battery again
3. Use a Canon lens.

DJI Mindy Posted at 2018-8-26 23:05
Hi there, we see you have posted in another thread and Susan has replied, our engineers are working with Canon to handle the SDK compatibility issues furtherly. It takes some time to optimize and test the compatibility, we'll try to figure this out through the firmware upgrade. Please also pay attention to the official website update announcement, thank you for your support.

Currently, you may refer the below to fix this temporarily. Sorry for this.

Hi there

As the user above stated, and as I'm prepared to validate, this happens with my canon lenses as well, like the Canon 35mm f1.4 Lii.

Also, I'd like to address your trouble shooting suggestions.

Step 1 yields no result, but most importantly this is information I've already provided in point #1 of the orginal post.  When your product is used to trigger the camera, when the camera goes into a a freeze, again the only thing that the camera responds to is PULLING THE BATTERY.  The power switch is UNRESPONSIVE.  I'll ask you actually read my post above before responding.  Because it makes users feel that you kinda just don't care.  Thanks in advance.

Step 2.  This is the only remedy, at the expense of corrupting my data cards.  This is obviously not a solution, but a temporary one, as you mentioned.

Step 3.  This step in particular that you suggested is a little insulting. And what it really shows is that DJI is not taking ownership of this issue.   Because what it assumes is that I am not aware of the bevy of complaints, including my own above,  from other Canon users with both Canon bodies and lenses exhibiting The. Exact. Same. Behavior.

DJi has a consistent issue of looking elsewhere to find culprits of their own issue.  This is an identifying characteristic of their early success.  It's obvious.

Rather than receive errant trouble shooting suggestions, I'd instead like to see that DJI is aware of the issue and is working with the major camera manufactures (without whom you have no product) to resolve the issue.

I don't even need an estimate of time.

Thanks again for considering these shortsighted release of necessary functions.

djiuser_kU8Zm6tYrKAA Posted at 2018-8-27 07:26
Hi there

As the user above stated, and as I'm prepared to validate, this happens with my canon lenses as well, like the Canon 35mm f1.4 Lii.

Hi there, thanks for your feedback, we sincerely apologize for the inconvenience caused by this problem, we have been aware of this and are working on getting it optimized with Canon company, we do not have an estimated fix date, but we are trying our best to improve our product, thanks for your understand and sorry again for the trouble caused.

DJI Mindy Posted at 2018-8-29 04:59
Hi there, thanks for your feedback, we sincerely apologize for the inconvenience caused by this problem, we have been aware of this and are working on getting it optimized with Canon company, we do not have an estimated fix date, but we are trying our best to improve our product, thanks for your understand and sorry again for the trouble caused.

Thanks of this response.  It makes me know you're aware there's an issue and it needs to be addressed. We look forward to seeing fixes in the future!

djiuser_kU8Zm6tYrKAA Posted at 2018-8-29 05:09
Thanks of this response.  It makes me know you're aware there's an issue and it needs to be addressed. We look forward to seeing fixes in the future!

Appreciate your understanding and patience.

Error 70 still occurs with firmware 1.5. What's going on??

djiuser_kU8Zm6tYrKAA Posted at 11-18 05:04
Error 70 still occurs with firmware 1.5. What's going on??

Hi there, we have just released a new firmware V1.6.0.50 and the issue should have been fixed, please update at your most convenience to see if it persists, thank you.

Mindy.  I can't believe I'm about to say this, but I'm very close to confidently calling this issue:  SOLVED. I've performed the update to 1.6.0.5.  After just a few minutes of somewhat rigorous testing that in the past has been able to easily replicate the issue of the Camera freeze that is only solved by pulling the Canon battery, I can now say that I believe this update has solved the 1DXii issues that I was experiencing when tethered to Ronin S via USB.  I cannot be 100% yet, but for now, I've spent 10 minutes triggering recording many times, and sorting through Canon menus making changes to ISO, shutter speed, frame rate etc, which in the past has caused the camera to crash).  But now I'm very pleased to say, the camera behaves normally with the Ronin S attached via USB (MCC-B).  I can say that's the case for both the Canon 35mm Lii and the Sigma Art 24mm, as of now. And I'll also add I'm connected via HDMI to the Atomos Ninja V, which triggers to record itself beautifully when I trigger the Camera via the Ronin S.  

I will return later to update this post with any additional issues, or to confirm that this is in fact totally Solved.  But for now, a great deal of thanks.  Maybe.

djiuser_kU8Zm6tYrKAA Posted at 11-19 09:06
Mindy.  I can't believe I'm about to say this, but I'm very close to confidently calling this issue:  SOLVED. I've performed the update to 1.6.0.5.  After just a few minutes of somewhat rigorous testing that in the past has been able to easily replicate the issue of the Camera freeze that is only solved by pulling the Canon battery, I can now say that I believe this update has solved the 1DXii issues that I was experiencing when tethered to Ronin S via USB.  I cannot be 100% yet, but for now, I've spent 10 minutes triggering recording many times, and sorting through Canon menus making changes to ISO, shutter speed, frame rate etc, which in the past has caused the camera to crash).  But now I'm very pleased to say, the camera behaves normally with the Ronin S attached via USB (MCC-B).  I can say that's the case for both the Canon 35mm Lii and the Sigma Art 24mm, as of now. And I'll also add I'm connected via HDMI to the Atomos Ninja V, which triggers to record itself beautifully when I trigger the Camera via the Ronin S.  

I will return later to update this post with any additional issues, or to confirm that this is in fact totally Solved.  But for now, a great deal of thanks.  Maybe.

Hi there, appreciate your feedback, yes, the new firmware has fixed this issue, please do more tests and let us know if the issue happens again, thank you.