Sim Rate in Career

Can somebody explain the sim rate.

I get simrate x2 or x8

or I get simrate x4 or x16

At the start of mission I can do simrate x2 or x8, but after some while, then I can only simrate x4 or x16.. anybody knows??

Like in the start you can do x2 and x8 and after it is not possible?? afterwards it is only x4 and x16…??

So this is my main question.., anybody knows why after a while I only can do x4 and x16… and not anymore x2 and x8 … why

No idea. Maybe a mod is messing something up? Mine works fine as of earlier today. I’m on PC.