First step in fixing this issue (if you have not done so already):
Replace the stock SD card. Their have been known issues with them for years.
Second step:
Revert to FW 1.6.
Also take a look at the card usage on the printer:
On the P1x panel > Settings > SD Card: (mine says 10.2/57.9 GB)
If the card is approaching being full, it might be time to replace/reformat the card. I don’t know what kind of affect an (almost or) full card would have since I have never had a card survive that long, but it’s worth a consideration.