Can’t edit screenshots

I can’t edit screen shots, or really anything else in ipad. Every time I try to edit ANYTHING I keep getting a message saying “this picture is not editable, would you like to duplicate and edit?” And I choose yes, edit it but then it just saves the original when I’m done. This happens over and over no matter what duplicate I select. They’re not pictures synced to an album anywhere, they’re not from my computer and they’re not saved from the internet, they are screenshots of text from my Pages app. When I do this exact same operation on my phone on the exact same file, it works fine. It’s just the ipad that won’t let crop or edit ANY PICTURE of any kind at all. Any ideas what might be going on? It’s really aggravating because I know for sure I was able to do this last night on the same file, I just can’t do it now.