Manually tagging video causes erratic behavior

When I manually tag a video with a face, the circle appears in the center of the screen as expected. When I then move the circle over the person, the circle shoots off-screen to the left.

It's then broken and displays just the X and editable name. There's no longer a circle and no way to move it back on screen. The X is not functional, so no way to delete the tag once it's in this state. It happens every time, on 2 different machines and is completely unusable for tagging people in videos.

If I make the circle really small and drag it to the far right, then when it shoots to the left it stays on screen and isn't broken. It seems to have some offset built-in which is making it adjust itself to the left when the mouse button is released and if this takes it off screen it's completely corrupt.