SAPLOGON.exe ignore theme change

We are using SAP GUI 770 patch level 4 and for some users including myself the theme is not changed when I want to change the theme via SAPLOGON.exe. The originally selected theme is still displayed, regardless of which other theme I select.
If I change the theme via SAPLGPAD.exe, the theme is changed. The theme is also changed via sapsettingsshow.exe.
Question: What could be the error for this behaviour?

which is still striking:
If I have changed the theme via saplgpad.exe, the previously (old) selected theme is still displayed as the current one in the SAP GUI settings when I call it up with the saplogon.exe programme.
This means that the selected entry does not match the theme actually used.