I believe that the camera is okay, but the card is not compatible.
I had to deal with a similar problem on P1000. I bought Gigastone 128GB card (the same type I had been using for P900 in the past). I used a card in incremental mode, i.e., I did not erase anything, but kept adding files (pictures) to it. After a couple of months I got an error that the card could not be read by the camera. The same card was perfectly readable in the PC.
Long story short, after checking physical integrity of the card, I copied all files to the PC, reformatted the card, copied the files back to the card, and the camera recognized the card and the files. But after a few weeks of using it the error happened again.
I tried it several times (over a couple of months) switching between two identical Gigastone cards. I observed the same behavior.
I switched to SanDisk Extreme Pro (also 128GB), and for last 1/2 year there was no single error.
I have some suspicions on what may be happening, but they are way too technical. They belong to an electronics forum, not to a photography forum.
Bottom line:
some of the SD cards are not compatible with P1000. (Duh...

) P1000 has different SD card interface than P900, and the fact that the card did work with P900 does not constitute the fact that the same card will work with P1000.
A comment about formatting SD cards:
SD Card Association recommends not to format SD cards using computer built-in formatting procedures, but to use dedicated SD cards formatter developed by them (or rather for them). You can find the tool and the explanation why in their web site:
https://www.sdcard.org/downloads/formatter/index.html