Hello guys! So, I started Launchbox 12.15 today and configured it for the first time, so, I'm not sure if it worked before and it's broken now or if it has always been this way.
Long story short, I started with a few C64 games and they were displayed fine. Then, I copied a few more in the very same folder and went to Tools->Scan->For added C64 Roms and Launchbox couldn't find anything new. So, I did it again - same result. Exited LB and started it anew, scanned again, still nothing.
I had to do the import process from the beginning (Tools->Import->Rom files etc) for LB to finally find my 54 new games and add them to the list.