I’m sitting in the non-modded Twin Beech right now and I’ve got the compass light turned up fully and the HSI remains dark.
Looks like the Denarq mod fixes that.
I wish Microsoft would come back and fix a few of the outstanding issues on some of these earlier Local Legends/Famous Flyers.
EDIT:
This bug wasn’t even in the bug reports. I’ve added it. It also includes the clock light being non-op.