Apple Watch 5 - no heartbeat info to fitness apps since november 2020

Anybody having issues with heartbeat monitoring during workout? Tried everything in following apps: Mapmyfitness, Nike run club, and Apples own app. Until november 2020 I received very detailed heartbeat information during workouts, which allowed me to study heartbeat development by the minute. Now I either get nothing or some vague average heartbeat, that makes you want to run through to the doctor’s. All apps are up to date, watch is up to date, IPhone 12 Pro is up to date. Any suggestions?