Hello everybody,
I am having exactly the same issue as here display-settings-not-working-as-exspected. It says in the thread, that it was fixed in 1.18 version, but I am having this now on 3.0.1-a14.
So in short, when selecting option for 90hz it changes the refrez rate properly. However, when closing screen and opening again, the refrez rate is not 90hz anymore, even though it shows that still in the settings. Wierdest part about this is the fact, that opening camera app puts it back to 90hz, until I close the screen again.
Anyone else having this issue?