From the moment I purchased and received my flipper zero I cannot find a way to update the firmware without errors, crashing, missing files, the SD card “Disappearing”, and so forth. No update i have done via bluetooth, zflipper, difference computers, and different OS. Nothing seems to work. I cannot figure out why I consistently get one or more of these issues every time.
What brand and size is your SD card? And try a different one, as it sounds like the one you are using is causing some issues.
I think it’s probably the culprit. I have another one coming. I suspect that will solve the problem.