Thank you all for the suggestions!
I don't think short presses on the datapanel is the issue. They all seem to register. I did try to do everything with long presses but it still does not work.
I have not bound any of the datapanel buttons (numbers or LS, MÅL) to any keys on purpose. I revied all my bindings and could not see anything obvious that would cause this. I also tried to unplug my stick, throttle and pedals and still got the same behaviour. So at least none of them have conflicting bindings.
I do insert the data cartridge before loading it.
I also tried a few different air bases but all with the same result. I started an instant action mission and tried to enter a couple of different air bases by code "90XX" but I can't get L1 to show when pressing L/MÅL.
I recorded a track where I start up the jet (skipping any proper procedures to get it up and running fast) and then load the data cartridge and review the loaded data. You can see me stepping trough the flight plan and both LS and B1 looks good and can be selected, but L1 can not. I also look at what data is loaded for the three (LS, B1, L1) waypoints in REF/LOLA and Bana/GRÄNS and everything looks correct. Airport reference numbers, runway heading and TILS channel.
It sounds on you guys that what I have been doing should work. I think I might try to reinstall DCS and hope that will fix this since I seem to be the only one who has this problem. no_L1.trk