From some time ago, I find that some covers from books bought in the kobo store are substituted by generic ones in the Initial page and in the library (not in the book itself).
After a synchronization, the original covers are recovered, but after a couple of power cycles (not with the first), they are lost again (with wifi off and then no synchronization at all).
Looking inside the thousand folders with covers, I am able to find them (not easy due to the strange name), but no way having them shown. Maybe something changed in the database, but I cannot guess what it is triggering this behaviour.
Curiously, in the PC Kobo application, when I hit "details" for the affected books in "my books" page, the following message appears:
"Sorry, this item is no longer available. You can look for other items by this author or about this topic using the search above."
It seems that the book is no longer available, although it is still in the kobo store

.
Any help or ideas to solve this problem will be well received