Golden Ages not increasing cost

Hello, since last parch, previous of Brave New World expansion release, i have this bug.

The initial cost with 1 city for golden age is 500 , more if you found more citys. So if i cap to 500 when the 10 turns are off the count for the next golden age don´t go up. Is the same amount of 500. I think it was like +300. So for the 2nd golden age only with 1 city if all is correct i would need 800.

Mention that i dont have the expansion yet, i am playing with all dcs availables and Gold and kings expansion.

I have the suspicious that this bug don´t appear in BNW expansion.

So are more people having this bug?

This is like golden age is suposed to work:
"The amount of excess happiness needed to create a golden age on standard speed starts at 500, and increases by 250 for each previous happiness golden age that has occurred and 1 percent per extra city founded".

But when the 1st golden age ends, the count for the next one dont raise up to 750, it remains in 500. And so on for 3rd one that is suposed to cost 1000 but still remains in 500.