To learn how to use FDS, I started by importing the code from the flash_fds example. My application is using peer manager and I got really strange errors until I realized the flash_fds example is using key 0x7010 and file 0xF010. The file id is within the forbidden range of peer manager (keys 0xC000 to 0xFFFF, file id 0xC000 to 0xFFFE).
I suggest the flash_fds example chooses another file id to avoid this error in the future.
I agree that it would be better if the FDS example used a file ID outside the Peer manager reserved range. I have created an internal ticket so that this can be improved in a future SDK release.