The last few times I’ve used the garmin & HRM it seems to be reporting heart rates of >210bpm, so seeing as I can’t actually see my heart beating outside my chest I’m assuming that its not registering correctly.

I’ve moistened the patches on the strap but it doesn’t seem to make a difference.

Anything else to try?

Premium straps are well known for throwing a wobbler. Some have fixed it by fitting the Polar unit to the strap or just using the standard strap

Balls.

Well I might try changing the battery first otherwise new strap time 🙁