Switch behaves different after certain time of day

This problem is causing me a lot of frustration; I have a fibaro double switch which used to work fine. But lately the second switch send the wrong scene data.
Most of the time it works fine and sends the data for single or double click but in after something like 21:30 it sends hold and release (I see this in the OZWlog). And when this happens my automations no longer work.

It must be an OZW issue cause I see the incorrect data in the logfile. Does anyone have an idea what might be the problem? (The first switch works fine all the time).