I posted this issue a few weeks ago in the PvP section but got no feedback from ZoS.

https://forums.elderscrollsonline.com/en/discussion/535478/is-mist-form-bugged#latest

I'm now raising it here.

Essentially mist form doesn't always trigger when selected while in combat.

Here is a video of it failing:

https://youtu.be/b_bPSdoqcPY

I'm happy to post more videos if more evidence is needed.