I use a Coros Pace 2 smart watch, which can send the measured Heartrate like a sensor. In STAmina app I then use the Assistent for incompatible Sensors. The assistant recognizes the watch and also displays the accurate HR in Realtime with correct changes and so on. Also when i finish setting up, the HR is displayed as a number.

As soon as i close the Assistant and try to record a new PB for example, the watch is still in the connected devices, and listet as "connected" but no HR is displayed but just "---"

I tried restarting my devices/apps, also repairing - nothing helped