Update on my own issue:
Decided to downgrade to 1.20.0 and disable the updater. This turned out to be a great idea!
The bug with the subs is gone and even better is, I now get 40 FPS encodes up form 13.5 - 15 FPS.
Whatever the diffrences is on the versions above 1.20.0 there seems to be some huge changes.
As I don't care for H265/4K stuff I don't know if there's a boost to this encode form - which some have been complaining about taking too long.
Try downgrading and see if that changes things for you guys aswell.
Anyways... Good luck!
Gryph