Excel 365 business - Impossible to save - "Errors were detected while saving ..."

Hello Guys,

Context :

- My company works on Excel 365 Business.

- Use on our local hard drive, on a shared server or even hosted on Teams to work on a file simultaneously.

- The problem is recent (2/3 months) and relatively rare (less than 10 times in 3 months).

- The problem is also random (different computer, appearance of the problem on our 3 working methods - Local - Server - Teams).

Symptom :

- Unable to save the file regardless of the recording format.

- All our work is lost. This represents 1 day of work that cannot be replaced => This is an Excel file that we fill out when we go to clients).

Additional information :

- One of the files with this problem may have been backed up with Office 2013.

- When the file crashes, we do not necessarily have a message when saving. It is when the file is reopened that we can no longer save it.

- The computers are up to date (Windows, Office, Hardware drivers, Bios, etc.).

- Our Excel files models got Macro

Thanks a lot