Hello Olivier,
You should be able to open a simple square surface. Try to set all settings back to default by doing the following:
- Close all WB.
- Type %appdata% in Windows file explorer and press enter.
- Go in the Ansys folder and rename the v231 folder to v231_old.
- Restart WB. This will reset WB to default settings.
If this doesn't hep, I would try to uninstall and reinstall WB 2023R1.
Is this the student version or the commercial version?
Reno.