Movement glitching?
Something like what you describe has been happening to me for a couple months now.
I’m in combat and without any obvious cause I’m suddenly unable to move. My character can change the direction they’re facing, I can still fire off skills, but I can’t move.
Using a movement power or dodge usually gets me out of this.
Since it’s been so random and I have no idea how to accurately reproduce it I haven’t been that keen on reporting it as a bug.