Chronos disconnecting and reconnecting from HRM-run sensor when also using Edge-800

I have both a Garmin Chronos and a Garmin Edge 800. I use these two together when biking, in combination with HRM-run sensor. I have found out that when I use both Chronos and Edge together, the Chronos has trouble keeping the connection with the HRM sensor. It disconnects and reconnects several times in a ride. I do not have that issue when I am working out with only the Chronos and the HRM-run. The Edge-800 does not suffer from this issue under any circumstances.

Is this an issue with the watch or with the HRM strap? 

Do more users of Garmin watches experience troubles with this?