Total War: ROME II - Emperor Edition

Total War: ROME II - Emperor Edition

Para Bellum - Campaign
Why confederating leads to negative income?
Hi, I have a cheat called "AI accepts all offers", which means if I put it on the top of the mod loading list, this ensures that the AI will accept whatever I ask.

So I loaded Para Bellum mod, and I play as Cyprus. First end of turn led to my overlord Egypt getting attacked by Seleucids. I broke the alliance with Egypt. Next turn, I was able to make Seleucids join my confederation. This led to a predicted positive income of 2000 or 4000 per turn, I forgot which one it was.

Next, I annexed Knossos and Rhodes, by asking them to confederate. This actually led to negative 2000 income predicted. I disbanded all the military of these two islands (Crete and Rhodes), but still the income was negative 1500 predicted.

Why is that annexing Seleucid did not lead to negative income, but annexing Knossos and Rhodes did?