Budget plummets as soon as I hit Capital city achievement!

[Boerentoren]

Hi all, got a real nasty situation here.
My city was doing fine at 35k pop, I didn't have any major traffic problems and I was making a steady 5k profit a week. As soon as I reach the capital city achievement (36k pop) my budget plummets to -1000 a week. How is this possible? I already tried reloading to make sure I hadn't done any expensive stuff.

I am Using the Proper Hardness mod (normal mode). I haven't had any bad experience with it so far. And I don't know if this is related.

Please advice.

 

[Kharisian]

The vanilla game changes at 30k, and only provides the change of a lump sum payment (you get a lump sum as well) when the new milestone is reached, a new area, and ship connections/buildings. None of which should have overly impacted you in a negative way. I'm betting this is the result of one or two mechanics that exist in the proper hardness mod, but I might be wrong.

The mod is designed to have a "wealth counter" which is impacted by various factors. This can impact your income. Is there a "land value" warning over any of your buildings? Select some buildings and check the wealth level to see if it is being impacted. If it is lower than expected then you have found the culprit.

Happiness also impacts income. Income can also be lowered in the hardness mod by long commute times. Check to see how loaded your transit systems are, or if your city happiness if low. If it is low, the solution might simply be "more buses" and "more parks" or "better access to services."

If those are not the problems, it might be worth taking a closer look at the city graphs to see if those show a problem.