Strange telemetry losses with Micasense RedEdge connected

I have following issue with a RedEdgeMX and Mission Planner, connected to a Pixhawk1 with a serial connection (serial4):

Everything works ok so far, the Rededge seems to get the needed telemetry data from the Pixhawk.
But in Mission Planner, there is a problem during flights. Mission Planner is loosing the telemetry connection to the Pixhawk (in some cases). Or it is failing to update the uav’s position (in other cases).
That always happens a few seconds (up to 20 seconds?) after the mission starts. Not at once, but always short time after the mission starts. The mission itself is not affected, it goes on till the end and the RedEdge makes all needed pictures.

This happens only with the RedEdge connected. We also use a FLIR for example, also connected in the same way to Mavlink. With the FLIR, there are absolutely no problems.

The telemetry link is a dual link via WIFI and TBS Crossfire. On board of the drone, a Raspberry Pi with Mavlink-router is running. On ground, a Raspberry Pi with Mavproxy does the link management and the laptop with Mission Planner connects to the Mavproxy using USP. This combination runs reliably for two years now.
What makes me wonder: when I connect the RedEdge, why there are always two „Cameras“, one with Mavlink ID 255 and one with ID 1.

Anyone who has any ideas or hints?

No, that is not the cause of that issue. The link quality of the telemetry is not affected.

You only see sysid 255 when using the problem camera? If so sounds like gcs messages are being bounce back from the camera. Which should not happen. Or its a routing issue

Mavlink sysid = 255 is a GCS id and sysid = 1 is a Ardupilot standard UAV id.