MAVLink via serial 4/5

I’m running copter3.3rc5 and trying to connect for MAVLink data on serial 4. I’ve tried adding the commands to etc/extras.txt and I’ve also tried setting SERIAL4_PROTOCOL and SERIAL4_BAUD. Is anyone using MAVLink on Serial 4/5, or should I just use a splitter on telem1 or 2?

I am having the same issue. I also tried to enter the Mavlink command from NSH terminal, but Mavlink app is missing there.

Did you find any solutions?

Any news regarding this issue?