Problem with Paper: disappearing papers

Hm, okay... unfortunately my Android phone would be the main device I'd use those papers on. I only used the Windows PC to setup the documents more easily (with tables etc.). And btw the problem with papers not opening also happens on the PC.

I will make a copy of all my papers using the web interface on my PC, delete the original ones and then only use my Android phone to read the documents, not to edit them. Perhaps the editing on the phone is causing the problems...

EDIT
Just copied the three pages into a subfolder within Dropbox (all using the web interface), deleted the original ones, moved the copies back to where I want them and now all three papers can be opened in Paper when I click on them in Dropbox. I can also open them directly from the Paper app on my phone: I don't really dare to open them from my Dropbox app because I am afraid that anything I do with those files on my phone will cause problems...

So things look okay for now but I can't say I trust the entire system... I certainly don't dare to edit the files on my phone anymore which is a shame because that's what I was planning to do. Thinking about using something else for this (Google Docs, Evernote, MS OneNote, not sure yet.)

Dropbox never failed me in the past, I have to add, but Paper is another story.