So I'm stuck with Windows 10, and I guess you are already aware of the audio problems. Having several second lag on all sounds, so havn't been able to work much with MarkV lately.
My most recent map uses a lot of new mdls some with alpha masking. MarkV can handle all except for one. There is a seahorse with masking on the wings and fullbrights intentionally painted on the stomach for glowing effect.
QS and QSS can render it properly:
https://i.imgur.com/IsHhNhI.png
But MarkV will display the fullbrights as solid black:
https://i.imgur.com/m936Lf6.png
Its a shame, as its the only one it won't handle.
Here's hoping that a fix comes along one day.