Dynamic Lighting locks and moves around the map

This is a hard problem to describe, so I took a video of it. In general after I move a little at the start-- in a game where I am a player-- the dynamic lighting 'locks' like so and I become unable to meaningfully interact with the dynamic lighting. It fixes if I refresh it, but only until I move my character once or twice, at which point it locks again. A video of the problem. I truly have no idea what's doing this or why.

Hi satchTwentythree! I don't remember ever seeing anything like this. What browser and platform are you using? Is it only that page that behaves that way? Only that game?

I'm using Firefox, and this is my only jumpgate game that I'm a player in. I can test and see if it happens in the one I run, though I haven't used the dynamic lighting this way much.

A second video of the problem,  this time in my own jumpgate game. I entered preview for a character's perspective, and in the midst of dragging her around you can see that it abruptly locks the shadows in place, flips me back to GM view, and when I click Exit Preview nothing happens. I have no idea what would be causing this.