Tag Selector in Composer not Y-Scrolling

I’ve tested this on several themes including the Default theme.

It still scrolls on my discourse on v3.1.0.beta6 +179

But not on my discourse latest release +16

Instead, the Topic Post behind the Composer does scroll up and down as I move the mouse wheel in within the Tag Selector.

However the Inspector shows it’s set to

overflow-y: auto;