Edge 1030 plus + HRM pro dropouts

Hi All,

  I've been seeing dropouts between my HRM Pro (v8.8) and Edge 1030 plus (v6.75).  See image.  Battery status of the HRM is reported through Garmin as good - the battery is certainly a relatively new replacement, so I believe it.

Looks like it's connecting via Ant+, at least from the sensor page on the edge.

Any thoughts would be appreciated.