Buttons move off portal and onto tab surface

I have a portal within a tab.

Each portal row has a button bar.

The buttons open popovers associated with the portal row context.

If I change the layout of the popover, the associated button bar on the portal often disassociates from the portal row and jumps onto the tab surface.  At that point it only shows in one portal row (the first), since it is back one layer.  I have had a big problem getting it back where it belongs, sticking to the portal surface.  I have dragged it out to a clean non-tab surface, I have tried copy pasting it back into place, moving it up down with the mouse, bringing various surfaces and objects forward and back, etc.  Only recreating it from scratch seems to work.  This is an intricate button and it's becoming problematic.

Anyone know a technique to force the association of a button bar with a portal surface rather than an underlying tab?

(I have noticed that my scheme gets messed up when the popover I am modifying extends beyond the portal, e.g. hanging out over the right side.  At that point, if  move a field in the popover, the button becomes unhinged, even though I never moved the button itself)