Bug when searching for books in the Android app library

For over a month now, I've noticed a bug when searching for books in the Android app's library.
When I type in the name of a book that I know I have, sometimes the book doesn't appear in the phone's library. See the images comparing the computer library and the Android app library.
I've already cleared the cache memory and “force stopped” the app to see if it would work, but it doesn't.

Note that the only resource that appears is one in the “Print Library”. The others I have don't appear at all.
I don't know if the problem is restricted to the Beta, but since the Beta version is installed on my phone, I decided to post it here in this forum.