Custom SQL reports don't return data in another language anymore

Summary:

Four users with the same security roles and Area of responsibility ran a report. 2 English-speaking users saw data, while the 2 French-speaking users no longer see data. The report code did not change since it was created last year, and it worked fine.

Caches were cleared, they logged out and logged in a few times to no avail.

The French and English users have their language settings preferences set up correctly for the Default, Current Session and Display Name.

In the Report Catalog, under the employees' My Account, Preferences are also in French by default.

Any idea what could explain this?