HRM stable on bike, flaky on run: AppleTV

I use AppleTV for Zwift. My Bluetooth HR Monitor works flawlessly while on the bike. While using the same HRM while running on my Nordictrack treadmill, I get frequent drops, high/low readings, etc. 

I suspect there may be interference from the treadmill to the AppleTV. Any suggestions on how to avoid this? 

Thanks!
@Kid