Many issues can result in laquar. Mainly manufacturing issues.
But in all cases to be positive solder is makinga good connection need to verify points are clean, no matter what it doesn't hurt to scrap them lightly.
I've seen a few 1.2, no scrapping need then another 1.2 that required. If you look at teh motherboard you will sometimes see hole( solder point ) covered with laquar. Sometimes slight heat from soldering iron will remove and cause a connection, other times soldering iron melts laquar and wire attaches and joins laqur looking like and feeling like its secure.