Proportional editing in UV editor acting weird - possible bug?

I’ve attached a blendfile with two objects, both with weird behaviour in the UV editor with proportional editing on:

Object 1: Hit tab to go into edit mode, G to move in the UV editor and you’ll see another vert moves along with it. Proportional size is set very small, moves even if you scroll down to zero.

Object 2: All verts move when you try to move just one.

Weirdly, if i append those two objects into a new blendfile the UV editor works as expected.

UV_Proportional_Bug.blend (1.3 MB)

EDIT: Appending the Scene into a new blendfile results in the same weird behaviour…

Have you tried to turn off ‘Connected Only’ (in the Proportional Editing dropdown)?

Connected or not, with the proportional size all the way down the only vert that should move is the one selected, surely?

Had to download your scene to see it.
It’s a bug, but a little one.

The reason is that there are two selections being used at the same time, one in sync with the 3DView, and the other (that’s hidden) from the UVEditor.

Quick Solution:
Disable ‘UV Sync Selection’, select all vertices in 3DView (to make them visible in the UVEditor), unselect all vertices in UVEditor (those are the culprit ones), and enable ‘UV Sync Selection’ again.

Yep that seems to be it. Should it be reported as a bug, do you think? I’d never encountered it in my years of Blendering and it had me stumped…

I can’t replicate this behaviour in any way (which is kinda needed for debugging).

Perhaps your blender file is corrupt in some way.
I’ve appended your objects (just the objects) to a clean new file, and this behaviour was gone.

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Yeah the objects imported into a new blendfile work as expected, but if I import the scene into a new file it’s the same.

Very strange.