Validate yes, this is a library function, but it calls the USER_status function internally. It is intended in the library that this function should be redefined by the user, as well as all functions that have "USER" in the name.

I had the same problem. I changed the USER_status function in the user_diskio.c file and everything worked. The function body had Stat = STA_NOINIT, I changed it to Stat = 0.