You don't have to fully quit x-plane, there is a reload aircraft option in the XP menu bar, also a reboot button on the Saab side menu thing.
Normally clears that problem when it pops up.
I think the few cumulus are fine. I just did a quick test with a manual weather preset, changing clouds to few and there where some areas with lots of few clouds while right next there where huge gaps and some single puffs or smaller accumulations.
Same position, different heading: