Why have Stored pdfs disappear from iBooks in my iPad?

I have stored PDF attachments ( like bills receipts etc ) for my emails in iBook app on my iPad. They have all disappeared along with the books I have purchased and down loaded. All,the folders are empty but the folders I created to store different bills are all there. When I check for purchased books also I am not getting the list of books I purchased through iBooks. I routinely back up my iPad to the Mac via cable. But it seems I book items are not usually backed up in theses back ups ( according to the apple tech representative I talked to ) this has happened to me more than once. I am wondering if you are aware of this possibility and have a solution. Am I doing something wrong?

When you're looking in your iBooks app, at the very top center it probably says "All Books". Click that and make sure "Hide iCloud Books" is unchecked.

I could be way off but that was my first thought reading your question.

‘When you're looking in your iBooks app, at the very top center it probably says "All Books". Click that and make sure "Hide iCloud Books" is unchecked.

I could be way off but that was my first thought reading your question.’

I tried this and my ‘hide iCloud books’ button is not checked. I also have it listed as an iCloud backed up app.

Does anyone else have a solution for PDFs disappearing from iBooks? My purchased books do show up but other docs, such as receipts, account statements and craft patterns saved in iBooks are gone.

After reading this, I checked, and I can see all of the files I've stored in iBooks. If you backup to iCloud, you might check there? I hope you can find them... that's really frustrating.

I have just looked and over fifty% of my pdf’s only show on my oldest device !?

You might want to check with Apple Support...

They may be in iCloud, and you have to download them again. My pdfs disappear a lot. Sometimes I can't download them as they get grayed out. Doing a back up sometimes works. Signing out of iCloud, then signing back in sometimes works. Not sure why this happens.

I have had this problem for a while now and nothing helped. I tried signing in and out of iCloud, deleting the app and downloading it again, restating my phone. It did nothing. As a last ditch effort I just checked for a new update and 11.2.5 was available. I downloaded it and my PDFs that were missing reappeared. I never comment on threads, but I know how frustrating this was for me. I hope this helps!