I have noticed that when trying to attach xmas lights to a large tent, the lights automatically disconnect from either the cable reel or the generator.
The xmas lights cannot be attached to the tent while still plugged in.
When they are plugged into a generator or cable reed they don't light up, not even in hand.
I'm guessing something went wrong with the last few game updates either 1.12 (where xmas lights were updated) or 1.13.
place generator next to or inside tent - plug in xmas lights - TAB to tent menu - hear disconnect click - attach lights to tent - TAB out of tent menu - see that nothing is connected to generator - turn on generator - lights don't work.
OR
place generator next to or inside tent - plug in cable reel - plug in xmas lights into cable reel - TAB to tent menu - hear disconnect click - attach lights to tent - TAB out of tent menu - see that nothing is connected to cable reel - turn on generator - lights don't work.
Only tested this on Large Tent, not on other Tents but I assume it's the same process for all tents.