I keep checking my settlements on the pip boy to make sure they haven't been attacked or have problems.
Lots of times this is useful - I need more beds, food, water, etc.
Lots of times I get the exclamation marker next to happiness...
I fast travel there...sometimes I add a bed or take care of unassigned settlers.
Sometimes this gets rid of the marker...lot of times no.
I like how I can see who is assigned now...great improvement..
But the mystery of what the heck is wrong with happiness..is a puzzle still...
It could mean anything....imminent attack...too many unassigned settlers...
Maybe settlers are bored and want a bar set up and a store?
Sometimes they are just lonely and I visit and that fixes it...I'm guessing.
Mostly not...which is aggravating..
Like now..I get two settlements...usually bigger ones...happiness
I guess they are having an existential crisis or something..