Mullvad (flatpak) install does not launch using the dock icon

My first post as Manjaro newbee: I installed Manjaro Vulcan 23.1.3 and Mullvad browser flatpak via software install. Now the Mullvad dock icon will not launch the programme, but links are normally opened in the Mullvad browser. Also if I go to the software installer and look for installed programmes–>Mullvad browser and choose “launch” it launches.
Any suggestions how I can solve this problem?
Thanks in advance.