Pixhawk 6x with PRM-03 OSD

Hello Everyone,

i would like to use the Radiolink PRM-03 OSD with a Pixhawk 6x FC. The Firmware is PX4 v1.14.
Unfortunately the OSD only works on TELEM1, even if i configure TELEM2/3 and other Mavlink instances with the same parameters/baudrate. I also noticed some other behaviors that i dont quite understand:

Any help would be much appreciated!

Kind regards, Sebastian