I have just upgraded to Remote Desktop Manager 2026.3.9.0 64-bit (JIT), this morning and found that when I have the navigation pane unpinned, when I click on it from above as in previous versions, it does not expand and appears hidden behind the tabbed window already open. If I pin it, it works as normal
Version info:
Remote Desktop Manager 2026.3.9.0 64-bit (JIT)
Runtime: .NET 10.0.12
Platform: Microsoft Windows 10.0.26200
Workspace: Local Data Source
Allocated memory: 570 MB

I had same issue, more like Navigation put into wrong layer.