HRV Stuck at Null When Collected Immediately After Smartwatch Startup

Building a Connect IQ app that collects HR and HRV, I noticed an issue where HRV values remain stuck at 0 while HR is correctly collected. This problem occurs only when the application is run shortly after the smartwatch is powered on. However, it does not happen systematically, as I was unable to reproduce it consistently even after multiple consecutive attempts under the same conditions.

The only tested workaround I found to resolve this issue is to close the application and wait 15-30 minutes before running it again, or alternatively, to switch the smartwatch off and back on after waiting some time.

Since I couldn’t find an API method to reset the sensor, I tried disabling and re-enabling it using the same approach applied when manually closing the application. I tested different time intervals between disabling and re-enabling the sensor, including long delays of up to 60 minutes, but without success.

Is this a known issue? Is there any way to resolve it without having to manually close the application and wait 15-30 minutes or reboot the smartwatch?