This seems to be a quite known bug in Homekit. If you see the Flic wobble inside the Home app, then we have successfully delivered the event to Homekit and there is not anything more we can do at that point. If the action at this point fails to execute inside Homekit, I suggest you to go to Apple's support and tell them about this issue.
@Emil I found the error, and I'm not sure if I will admit it... But I had an old RPI running that I tested some flic buttons on some years ago (first release). Maybe I should clean up what I have running on my network...
I'm having the same issue. Had to re-enable the skill after a very annoying debug session. This does not happen with other smart skills that I have.
Can someone please resolve this? This seems quite basic and should not happen.