Update Error from Android App

Hi to all. We need help for a issue with new Andorid Samsung Tablet installation.
We have a new nextcloud user (Tablet5)…If I log with this user with an old samsung tablet (with same nextcloud app version and same Xodo Version), I can modify a pdf file and I can make a syncronization with next cloud server (Upload/Download).
With new samsung tablet, with same user I can’t upload modify. I receive updated files from nextcloud server but I can’t upoload? Why? I tried to double check configurations both new/old tablet and are the same. Crazy…

everytime if I make a modify to a pdf file, I have confirmation that file is saved, if I re-open file, it’s changed, but If I make syncronization I receive message “file is just syncronized” and file stays with old version time and date