Won't allow to backup anymore, Error Message !!

I have a OnePlus 5 T, Android 10, now when I try to backup my file to the download folder, it says ERROR, could not write file, any suggestions. ❓

Here is what I have tried, I tried editing each note and saving, I tried foreclosing the app, cleared the app cache, I even moved the existing backup to a folder, and nothing seems to work, keep getting the same error message. 

I don't want to uninstall the app, then Ill loose all info on it. I guess I can C&P and uninstall then redo from scratch, but unfortunately it doesn't allow to do that with the Excel files.

I did post yesterday, but for some reason it's not showing up in the forum, so I did another post here, hope this works, I did also email the Dev


See error message from Pic

I guess no takers on this, so much for support from the Dev on this app, that tells me a lot, cheers