itch.io

I just stopped by this page again after about a year to see if an update had been released and the more info  drop-down says this was updated 13 days ago!?!  Was that because of 3.0.2 instead of 3.0?

Two ideas, well three actually.  Try plugging your device into a computer and see if you can use that to copy and paste files where you want them that way.  Or just maybe use the Move option instead.  Also you could maybe just "Back-up" your save files and use those ones instead.  You might need to grant more permissions to whatever file management app you've been using on your device or try getting a different better one, you'd be surprised to find how much higher level access some 3rd party file apps have!  

But really it sounds like one or more of your saves is corrupted or something and I'd first try moving one at a time even if all the ones you start off trying throw up that same message does not mean that they all will, so just keep going down the list.