After reading here that if you complete the Nuka World main quest before rescuing Preston from Concordia you might stay friendly with him while also running the Nuka Whole gangs, I started a new game to try that.
I made my way to the Nuka world transit directly, I did no quest in the Commonwealth at all, not even talking to Codsworth or Dogmeat. I only cleared a few locations without quests for the basic weapons and level needed to fight at Nuka World.
At the Home Sweet Home quest however, when I tried to talk to Shank to expand into the Commonwealth, he claims that there are no target available for both negotiations and assault.
How do I proceed from here or is it a bug that requires me to load and earlier/clean save?
Except Sanctuary which I believe is not a valid target for Nuka Raiders and Sunshine Tiding co-op, I have not visited any settlement locations. I cleared out Sunshine Tiding co-op and interacted with the Workshop but did not build anything, merely to claim it's content.
My game is modded including several mods that increase some settlement's zone for building and allowing scraping of more existing items for space to build(I'll update the actual mod's name later).
After talking to Shank I did attempt to return to Commonwealth and establish some settlements including Tenpines Bluff, The Slog, Croup Manor, Abernathy farm, Greentop Nursery and Taffington Boathouse - having a minimum of 3 settlers and still actively recruiting. But none of them became available targets even though all four of Shank's recommended settlements are within the list.