Editing files no longer works

I'm trying to edit a file (stored in my Files app) that I edit and use every month; up until now I was able to make changes to update it and for some reason this time I can't. I haven't updated the iPad I'm using in a while so nothing substantial has changed. No one else has access to these files, they are all created by me and changes will only be made by me. I tried going into Pages, where I created the file, and that didn't do any good because the file is now stored in my Files. I'll try Numbers next, but I anticipate the same issue, as the file is stored in Files. If anyone has any great ideas, I'd love to hear them. Thanks!