Developer Tools API Explorer

I am trying to use the API Explorer within the UI of openHAB. When I click on it (Developer tools → API Explorer) I get an empty window.
I checked the log and found:

2024-04-01 17:16:47.492 [ERROR] [] - Error while authenticating
java.lang.NullPointerException: Cannot invoke “org.openhab.core.auth.UserSession.getRefreshToken()” because “s” is null

I searched the web, but I could not find anything related.
Running openHab 4.1.2 on Windows 11

Restart OH and clear the cache on your browser and if the problem persists please file an issue on the openhab-webuis repo.

Just submitted a ticket, clearing cache did not help