I found a fix with the spectrum radio. It seems the mission planner 3.5 & later does not like RC minimums and maximums at 1100 and 1900 exactly. Many people have had this RC issue, I have read some strange fixes and some people are looking for version 3.4 still. I adjusted my travel to 99% for all my channels and the error is gone.
It’s nothing to do with mission planner.
Just set minimum to 1 more than it is…