I'm wondering if there is an issue with certain CF Express B cards and the Ronin 4D.  Mine won't recognize my Angelbird AV Pro (1TB 1700MB/s) OR my SanDisk Extreme PRO 256GB cards.

Hello, there. Sorry for your inconvenience. Would you please mount the CFexpress card to another camera to see if it can be identified. If not, please use the DJI PRO SSD mount and DJI PRO SSD 1TB Card or another CFexpress card on the compatibility list for testing.
Please tell u your feedback after trying. Thanks!

DJI Wanda Posted at 2-23 20:33
Hello, there. Sorry for your inconvenience. Would you please mount the CFexpress card to another camera to see if it can be identified. If not, please use the DJI PRO SSD mount and DJI PRO SSD 1TB Card or another CFexpress card on the compatibility list for testing.
Please tell u your feedback after trying. Thanks!

Thanks.  So the SanDisk started working after 5 tries but the Angelbird does not.  It has on occasion recognized the AngelBird but freezes when formatting it at about 20% formatted.  Using USB C to an external drive works fine.  
The Angelbird works fine on my Canon R3 and R5.
I do not have the PRO SSD.
Thank you.

Mine is working just fine. Got the 512gb version. I had to format it first on the Ronin 4d tho!

I have the Angel Bird 256 GB and the 4d is also having problems. It recognises the card occasionally and I immediately try to format in the  camera but this fails.

fans88782e24 Posted at 2-24 08:28
I have the Angel Bird 256 GB and the 4d is also having problems. It recognises the card occasionally and I immediately try to format in the  camera but this fails.

Just tried a second Angelbird 1TB card and it has the same issue so this clearly is an issue with the Ronin 4D interfacing with this brand/make of card.  Although at first I had issues with the SanDisk Extreme Pro card, it was only after trying the Angelbird and upon rebooting the Ronin both the 265 and 128GB Sandisk cards work fine.
I would expect a firmware update to the Ronin will address this issue.  Until then, the Angelbird 1TB AV PRO CFexpress B card (1700MB/s) does not appear to work with the 4D.

JWKITCH Posted at 2-24 04:10
Thanks.  So the SanDisk started working after 5 tries but the Angelbird does not.  It has on occasion recognized the AngelBird but freezes when formatting it at about 20% formatted.  Using USB C to an external drive works fine.  
The Angelbird works fine on my Canon R3 and R5.
I do not have the PRO SSD.

Thanks for your reply. For now, the recommended CFexpress 2.0 Type-B storage cards are as follow

The model of AngelBird you mentioned is not on the list for now. We will forward it to our designated teams. Thanks for your understanding and support.

Will this list be updated with the June Firmware? Give us some love and let us know if we should keep the card we have. Just want to use my product to its fullest and can not. 6K should be available via USB C like many other cameras that even produce full 6k at 60fps