COM2 and NAV2 unavailable

[r2p2]

This might be a stupid question but while flying in cruise I stepped away for a minute from the flight deck ... talking to the passengers ... when I came back I saw that COM 2 and NAV 2 frequencies are crossed out in the PFD and COM2 also in the middle screen. I thought there might be a defect which would be odd after just 18 hours of flight but maybe its a monday model.

After landing, I checked the maintenance hanger but every part of the avionics is "as new".

Am I doing something wrong here?

Thanks in advance for any hints.

[r2p2]

It works again after restarting XPlane... That's odd.