They did allow me to short-check my bag to KUL without issue. Not sure if they would have done this by default but after standing in line 1.5 hours just to check-in (don't get me started), I just asked the desk to do it before they even saw my overnight connection.
The weird thing is they printed my onward BP for KUL-SIN the next day and then literally ripped it up in front of my face and said, "Get another one tomorrow at KLIA." I have no problem getting another one, especially since I'll need to re-check my bag, but the way they did it was super odd.
-RM