I run an iPad Mini on my controller, and all was good. Until one day when I hooked up as normal and the Go app reported a fault on my SD card.
I tried to format it, and got the same error. I tried several other cards, but all had the same error. Everything else seemed ok - the camera & gimbal worked (in as much as the iPad displayed from the camera). But I just could not record. In desperation, I factory reset the Mavic - and was met with a gazillion errors. And still couldn’t record or even take stills.
Facing a return to the shop for replacement/repair, I was pretty fed up. The next morning I tried a different USB cable to the controller. And the whole thing worked like a charm, straightaway. I tried the cable I’d used previously and there was the “SD card fault”.
So beware of unbranded cables. I’d never guess that a cheap USB cable could create such a bizarre effect - but it did. I’m passing this on in the hope that others will remember this if it ever happens to them.