Just had to replace the hard drive in my Dell Laptop . Running Windows 10. Downloaded the latest version of Assistant 2 V1.2.2.845. Unable to connect the Mavic Air  controller or drone  to A2 by way of USB .  I have connected other devices to all USB ports with no issues . Unfortunately I don't have access to another computer.  Thank You in Advance for Any  Help.

It is possibly a driver issue. You need to reinstall Assistant 2 after disabling signed driver enforcement.

How can I install drivers that are not digitally signed?
Windows 10 enforces driver signatures by default. This can be disabled to install drivers that are not digitally signed. Use the following steps to disable driver signature enforcement.
Click the Start  menu and select Settings.
Click Update and Security.
Click on Recovery.
Click Restart now under Advanced Startup.
Click Troubleshoot.
Click Advanced options.
Click Startup Settings.
Click on Restart.
On the Startup Settings screen press 7 or F7 to disable driver signature enforcement.
Your computer will restart and you will be able to install non-digitally signed drivers. If you restart your computer again the driver signature enforcement will be re-enabled.

Hi there, just a silly question, you had powered on the drone when connecting to the DJI Assistant 2, right? Please try to reinstall the DJI Assistant 2 and refer to the suggestions Jenee 2 provided. See if it works.

Jenee 2 Posted at 2018-3-1 22:14
It is possibly a driver issue. You need to reinstall Assistant 2 after disabling signed driver enforcement.

How can I install drivers that are not digitally signed?

Thanks for the reply.  Tried  several times with no luck . Might add when I first got my MA and downloaded an older version of assistant 2 everything worked great.  Since then I had to replace the Hard Drive in my PC and download the latest version of A2, is when the issues have started. Guess it is time for a trip to the Computer Store ?  Thanks Again for all the help.  

DJI Thor Posted at 2018-3-2 02:08
Hi there, just a silly question, you had powered on the drone when connecting to the DJI Assistant 2, right? Please try to reinstall the DJI Assistant 2 and refer to the suggestions Jenee 2 provided. See if it works.

Thanks for the reply. I did have drone powered up.  First got my MA with earlier version of A2. and before having to replace the hard drive in my PC, Everything went great. Just after the hard drive replacement and the latest version of A2 that the issue has started. Thanks again .  

Hi All. Just returned from the computer store and I have to say I Am A Happy Camper or should I say A Happy Flyer.  The issue turned out to be as simple as a Bad USB-C Cable. Who would have thought after only a few uses it would have failed.  Thanks Again for the previous input. Happy Flying.