Ambit3 Sport with Polar H7 - HR flatline issue

[Jeremy Main]

I’m very happy with the performance of a Suunto Ambit3 Sport that I purchased 2nd hand to replace two broken Polar M400’s.

Using my Polar h7 with the Amit3 I often experience the HR rate to flatline (see attached trace).

Is this a peculiarity of the Amit or the H7. Do you have any recommendations to fix this?

Regards,
Jeremy Main