Hi,
After editing a document or spreadsheet, and then immediately opening it again, OnlyOffice shows a Popup dialog “The file version has been changed. The page will be reloaded” and the document opens as readonly.
https://api.onlyoffice.com/editors/troubleshooting#key
I don’t know if this is an OnlyOffice or a Nextcloud app issue. FYI.
Cheers.
Chris.