Issue with using external heart rate monitor with Garmin watch

Hello everyone,

I've connected my Garmin watch to an external heart rate monitor, specifically the Polar Verity Sense armband. The connection seems to be solid as it shows as connected on my watch. However, when I go out for a run, the heart rate monitor on the watch remains active, as I can see it lighting up on my wrist. I'm unsure whether it's actually using the external monitor or still measuring from the wrist. Am I doing something wrong in the setup? How can I check if the watch is using the external heart rate monitor?

I appreciate any help or advice you can provide. Thank you!