I have been battling this problem for a while now. Both times it quit were on multi-day trips...difficult to fix anything.
The first time, I was told to check that logging was turned off after the first episode because the likely cause was the card was filling up. But upon checking, logging was not enabled in the stratux program. I was unable to flash my card using win32diskimage and wound up buying a new micro card, flashed it and everything was fine...until the next time.
Received the same advice this time but told to use Etcher to flash the card.
Etcher was able to flash the card that win32image couldn't and also the "new" one that quit working.
Researching this issue, I found a thread where it was suggested that shutting down ship's power to turn off the unit without shutting down the stratux program can corrupt the card. That thread suggested adding a short cut to your phone to shut down the stratux program before killing ship's power. I have done that and will add that to my shut down checklist.
I also notched the bottom of the stratux case to more easily extract the card without disassembly and stashed a spare card in my flight bag...just in case. No more getting caught 1500 miles from home without ADSB.