Bug Report : No Sleep data and no HRV since update 20.26

Hello community, 

I want to report my first ever bug from a mainstream update. 

I've recently updated my F955 to the current 20.26 version. 

Since then I have no more HRV data recorded as well as no sleep data. 

Are there any fixes available or is there a way to revert to the former firmware until this issues has been solved? 

Thanks! 

Tim