I play many custom games with default settings like Big Game Hunters against the AI, :
Example : If I have 9 starports, with plenty of room in between (on in those cases I tries stuck together also since they create only air units), if I mass create units, upon creation they stay stuck in place, I can’t move them, I can’t have them do anything. Yet other times everything works.
This happens mostly with the Terrans, but I see it sometimes with the Protoss… Any units created en masse with multiple creationg points (Warpgates, Starports, Barracks etc… …)
Yes there’s more than enough room between the creation points and where they rally to. Nothing is blocking their path. Happens with Air and Ground units.