So I pasted my city block full of foundries. I was missing 159 of them. I don't know if that helps or not.

It worked just fine, but after a bit, it stopped. Nearest repair turrets have full power. There are items in the network. However it won't build anything. It has just stopped.

IF i place the items manually, it works. Item placed.
However if I use Copy/Paste or Undo/Redo or Blueprints, it won't.

EDIT: it seems small blueprints work fine, but large ones don't. Small = 9 tanks. Large = 16. (at time of this typing)

I even took my 4x4 square of tanks blueprint, and deleted 1 row and 1 column. now that it had 9, it worked.

total of 27 tanks, 55 pipes, and 159 Foundries pending. I can build right next to them, no issue. I can even delete and manually place one with ghost cursor, no issue. Not a range issue, not a power issue, not a inventory issue.

EDIT: I deleted the ghosts of JUST the foundries (which I didn't have in the network) and the rest built immediately.

I have been battling this issue with large prints for quite some time now, It's in a much better place than initially, but sometimes it still gets stuck

the real problem is I absolutely want to avoid scanning with idle turrets 'just to see if there is anything' periodically, cause that would mean each idle turret would have some processing inherently tied to it which is no bueno, since I want to be able to support tens of thousands of turrets so only those actively in use should use any kind of scripts