So I have encountered a possible weird bug. I have been using Starlight drive in as my primary base of operations for some time now but after setting up a new settlement it seems I can no longer link any supply lines to star light anymore as the option is just greyed out but I can link a supply line to any of my other settlements. Also I can no longer send my companions to Starlight either as the option is also greyed out there as well. Is there some sort of limiting factor here that I'm not aware of? Does the settler population affect how many companions I can send to a settlement? Has anyone else encountered this or know how to fix it?

Settlement at max pop = cant create new supply line TO there, nor send companions

You need more beds there for a start.