Pinning a pane doesn't work

When I migrated from Toolkit Pro 10.4.2 to 12.0.2, I found that I'm having a problem with pinning a that has another pane attached to it.  The same code worked in the previous version.

To reproduce this problem, I have two panes in the same tabbed container with pane B attached to pane A.  I unpin pane A and both panes will hide into a sidebar.  I then expand the pane by clicking on the sidebar and then click on the pin for pane A.  Pane B will become pinned, pane A will expand again, but it will remain unpinned, the sidebar will still be shown. 

If I click on the pin button again, the sidebar will disappear like it's supposed to, but the pane remains in an unpinned state.

I have created the panes as follows:

pFirstVersionOnly = NULL;
dockingDirection = xtpPaneDockLeft;

#if defined(FIRST_VERSION)
pFirstVersionOnly = GetDockingPaneManager()->CreatePane(IDC_FIRST_PANE, CRect(0, 0, leftWidth, screenHeight/2), dockingDirection)
dockingDirection = xtpPaneDockBottom;
#endif

pPaneA = GetDockingPaneManager()->CreatePane(IDS_PANE_A, CRect(0, 0, leftWidth, screenHeight/2), dockingDirection, pUsedInWorkingVersion );      
pPaneB = GetDockingPaneManager()->CreatePane(IDS_PANE_B, CRect(0, 0, leftWidth, screenHeight/2), dockingDirection, pUsedInWorkingVersion );
       
GetDockingPaneManager()->AttachPane(pPaneB  pPaneA );


There are two versions of my product, in the first version, everything works fine. 
The second version doesn't work but I cannot find any other differences that might affect this.