[Catalina] Xcode 12 Sub-Tabs stop working (won't switch sub-tabs) after clicking on a XIB or Storyboard SUB-TAB

Version 12.0 beta 3 (12A8169g)

I'm facing a strange issue, When you activate (click) on a storyboard or XIB SUB-TABS (active sub tab appears in blue, below the main tabs), the SUB TABS all together stop working for the PARENT (Main) TAB, Even closing the Storyboard or XIB sub-tabs has no effect.

Restarting Xcode, everything works, UNTIL you click on a storyboard or XIB sub-tab and the problem occurs.

Basically once you activate a storyboard or XIB sub-tab, the other sub tabs buttons just stop working. Any one else facing this issue?

FB8205630