Unnormal Watt Performance

Hey Guys,
since my last two indoor bike workouts I observe a strange and annoying thing.

My tacx flux smart is connected with the standard tacx desktop app with an ant+ USB Stick and there I build and ride my workouts..the Watt Performance on the tacx App works fine. Simultaneously I Start the indoor bike App on my fenix 5 plus. The heart rate is connected with an external sensor at my chest. The fenix gets the RPM and the Watt directly over ant+ from my tacx too.

Since my last two workouts the fenix loses very often the connection and in my activitys I have Performances about 60.000 Watt .. It ruins All my Stats.. I ride Overall Watt about 5000...

Any ideas ?

Ty