I had a similar issue with a browser shortcut in /applications folder. When Pocketbook had a problem with some file in this folder it wouldn't display it again despite the file was edited and repaired.
Try to remove the file from PB, reboot the reader, copy the file back to PB, reboot again. Or to rename the file.
Here's the description of my issue: https://www.mobileread.com/forums/sho...d.php?t=196763