I’ve tried again. COM was on the current flight following frequency, NAV1 was on 110.5
Somewhere between LION and LOWG the NAV picks up LJB. This time I didn’t hear the identifier. After some fiddling I think I found what should have caused it, but I still couldn’t reproduce:
On the smaller display below the MFD, you can choose COM/NAV with the button on the right. When you then click Audio & Radios you get to your NAV1. If you look at the bottom right, it says to push the knob to get the identifier, and to rotate for volume. I might have done that while trying to zoom on the map while unaware it wasn’t on MFD setting. HOWEVER: If I try to hear the identifier now using this knob, I get dead silence.
Anyway, it seems it was a one time thing which I now should be able to reproduce but can’t
Thanks for your help!