won't start after a cold start

Bitdefender used to work fine until 2 weeks ago. No major change to my system besides Windows11 updates.

Now, Bitdefender will not show its icon in the system tray after a cold start and worst: right clicking on a file and choosing "scan with BD" will not do anything.

Only after a reboot will the icon show and the "scan with BD" work properly.

Thank you for your help.