iPad stopped opening xlsx and docx files

Upgraded iPad to Gen 6th. Upgraded iOS to 17.7. Did device to device transfer. Everything was okay Then later in the day, the iPad is unable to open Excel and Word documents. Completely lost any association. Clicking what is now a kind of greyed out file icon opens a blank page with filename and size in the middle. You can share it but the usual suspects like numbers, notes, freeform books are missing from options. Downloaded the Excel app and tried to open locally from files from the app, but the icons are just greyed out. The familiar E or W letters on icons also disappeared. Upgraded to 18. Same issues. Apple phone support recommended wipe and configure but without restore. Spend hours rebuilding and it worked at first, but couple hours later the file association disappeared again. Took it to the specialist. They said it could be the new chip not interacting well with iOS. Use Apple configurator to wipe it, restore it and see what happens. I also went back to the old iPad Gen 3, and now this iPad has the same issue.