Starting a thread instead of dropping it in the main comments.

Reinstalled everything. After a lot of testing it appears that when you move experience 5 musketeers and experience 1 espadachins who are at the far left of the unit roster out of a stronghold ikko ikki yari kumi and generic yari kumi respectively spawn. If you move them together they spawn as friendly kumi. If you move the exp 5 musketeers by themselves they spawn as ikko ikki yari kumi actually belonging to the ikko ikki faction. This is occurring on Tsushima island.

Yeah no idea why. I've hit the same bug twice now about 15-20 turns into the campaign. Didn't test it in detail the first time so not sure if the conditions were the same.

Load Order:
Lenny's Ship Campaign Movement
Lenny's Ultimate Weather
Lenny's Battletech
UEFC Major Faction Survival
UEFC 1.5 Unit Size
Lenny's Ultimate Jesuits
UEFC 1.58
Unofficial Patch 1.7