Edge indoor workout stops using grade from course after dropout

I've recently invested in a Wahoo Kickr V6 to use with my Edge 530. I have been following the same courses I cycle outdoors plus a few I downloaded online (gpx file imported in Garmin connect). Most rides are fine and quite realistic but I've hit an issue which happens at least once a week during rides.

After much investigation I've narrowed it down to the following set of circumstances. Midway during the ride the Edge 530 reports the Kickr is connected which suggests it must have been briefly disconnected (I can't remember ever seeing a disconnect message). Often when this happens the Garmin stops sending the grade from the course to the Kickr. What seems to happen next is totally random. Sometimes the Edge unit switches to either target power or resistance mode, other times it stays in grade mode but doesn't adjust the grade even though it is still following the course. It definitely is still connected to the Kickr as it sends the power, resistance or grade configured in the Edge unit. There is no pattern to this, it just randomly picks a training mode (doesn't matter what I was using last). When this happens I cannot find any way to change it to start using the grade from the course again, even though it is still following the course. I've tried changing the target mode back to grade but just stays at whatever setting is initially entered.

I am able to recreate the issue by turning the power off on the Kickr briefly. I don't believe the Kickr is actually losing power, I believe the issue is simply the Garmin is losing connection to the Kickr, which is connected via Ant+. Interestingly the Kickr is also connected as a power meter via Bluetooth and this does not drop. I am going to remove this connection to see if it makes a difference.

Other things to note.

  1. I also see similar short dropouts with my phone (iPhone connected via Bluetooth) on outdoor rides. Frequently the Edge tells me the phone is disconnected, I frantically check my pocket to ensure it hasn't bounced out then about 5 seconds later it connects again.
  2. I saw a post suggesting to remove the protective rubber cover I have around the Edge unit. I'll try that next.

Any suggestions?