I have experienced issues with collecting some builders and wished to confirm whether I am being a noob or am experiencing a bug.
The facts are as follows.
The builder NPC's are supervised by me.
I am at the same location as the NPC's.
I am on the ground with them.
I can see the NPC's in my party option.
When I attempt to join them to my party I get the following message. 'Unable to party with something at a different location.'
I have been able to party some.
This has happened at 3 locations
^ That error is typical of trying to party with something that's already in a party/squad with something else.
It's a known bug. You'd have to basically arrest those NPCs and free them to break the squad/party and have them act normally OR, find the PC who partied with / squadded them and have them break the squad/party.