Necessary mavlink topics for drone detection in QGC

Dear QGroundControl Community,

I’m developing my own flight controller and want to monitor telemetry data with QGroundControl.
My controller sends Mavlink messages and they are already displayed in the mavlink inspector view of QGC. Unfortunately, the corrosponding instruments (like virtual horizon for attitude) doesnt update and QGC keeps saying vehicle not connected. So there’s my question:

Which mavlink topics do I need to send to QGC in order to get a “vehicle connected” and my telemetry data properly displayed? I currently only send a heartbeat and attitude topic, which for APM planner for example, is enough.

Sorry for the maybe obvious to answer question. I’ve searched and tried a lot, but wasn’t able to manage it. Thank you very much for your help in advice.