When starting Visum it disappears at once or
the menu Scripts isn't shown correctly, e.g. a menu item like Python Console is missing.
Script menu was edited or
VisumAddIns or user-defined AddIns were added or deleted or
data for an AddIn was located in the according directory %APPDATA%\PTV Vision\%MAINPROGVERSION%\AddIns\
After that the related registry settings might be inconsistent.
It's corrected since Visum 22.01-09 (point 24023 in the release notes)
When Visum is closed delete the related registry settings under e.g. VISUM\220
Please note that user-defined menu items are also deleted and then have to be set again.