Why do the workspace tabs disappear when I switch to another tab from Layout? Starting sometime after blender-2.80.0-git.855b3e68ef27-windows64 - when I start Blender 2.8 I get the usual workspace tabs interface but when I switch from layout to some workspaces (UV Editing, Texture Paint, Shading, Rendering, Compositing, Scripting, Masking, Motion Tracking, Video Editing) the tabs disappear.
Modeling, Sculpting, Animation, Layout all retain the tabs.

I just downloaded blender-2.80.0-git.8df5e0eb66f7-windows64 today - still have the issue.

How do I fix this?
The problem is interface scaling. On my 4k monitor I had set the scale to 1.5. If I drop the scaling to 1.4 all the tabs are there for every workspace. Around 1.42 some workspaces have no tabs.

The 2/19/19 build (blender-2.80.0-git.855b3e68ef27-windows64) did not have the problem at 1.5 scale.

FYI