AI construction problem

[Q]

I thought first as you did, that the maintenance cost limit was reached. But that turned out to be wrong. Then I changed the AI construction vehicles file from a race that continued to build several items per turn to a race that only built one item per turn: no effect. I switched off the AI for one turn and then on again: no effect. And yes I am talking only about ships/units and not about facilities. It's a mystery to me!