There's an issue with "View: Show Compact Player" hotkey.
In compact player mode, if you open caption bar button menu, another hotkey is shown for "Switch to Main Player" command though your hotkey still works. But if you start MB in compact player mode, your hotkey minimizes MB instead of switching to main player. Reassigning the hotkey makes no differences.
Then I tested with a fresh installation. This time even if you assign a hotkey to "View: Show Compact Player" command, no hotkey is shown for "Switch to Main Player" menu in compact mode and behaves the same as described above.
BTW if you try to switch to compact player without any track in the main panel, you get this error:
MusicBee v3.0.5869.38705 (Win10.0)
System.ArgumentException: Parameter is not valid.
at System.Drawing.Image.get_Width()
at #=q9DbSqRPdv37bwllNpUsPygZ_jS4LBH4KZGEWWW1Ir1w=.#=qkQYyIrpyheOHqqLICcI9Fg==(Bitmap #=qdSIKFnZol7QhfO$pX3N7Lw==, Color #=q_NPthkE5omiscjebXozJCA==, Boolean #=qcKaPaL_dnbiK7YlrVKu1vA==)
at MusicBee.MusicBeeMain.#=q6d3WE3XquOZMTBV$2T8Aqg==.#=qh$Jhee8_DW$XywuuVc$n5$EkOG2gzxUCEWj42rmcrlo=.#=qpF3yZQdQZ0Q$iLeyLSD2ayQ61A08n7HTIDqCVMEOaWY=()
at MusicBee.MusicBeeMain.#=q6d3WE3XquOZMTBV$2T8Aqg==.#=qh$Jhee8_DW$XywuuVc$n5$EkOG2gzxUCEWj42rmcrlo=..ctor(#=q6d3WE3XquOZMTBV$2T8Aqg== #=qgaeAbwvdJ3PGjNEmAmRVbg==)
at MusicBee.MusicBeeMain.#=q6d3WE3XquOZMTBV$2T8Aqg==..ctor()
at MusicBee.MusicBeeApplication.#=qAEua7CkU6V$4HPnl4R_DZfXZGaf_yORT8QInVUP34n0=(Boolean #=qRrjV8OjVCjONZOkk7ME7Cw==)
at MusicBee.MusicBeeApplication.#=qVUmUKgdAcHngerlU6srUcQ==.#=q7qRr2KU0PYDuKXVs76tXQg==(ApplicationCommand #=qPcX4XTPI1jUOgsBZb2CKRQ==, Object #=q9IUeJ6iwWCh6muA7vV1PcQ==, IList`1 #=q6VrWzcR734aq1twvoi1$Cw==)
at #=qEkasraVmzdZHML2y$ybRuVxYp5d6j_EQQlY5Jc4$7$w=.OnClick(EventArgs #=qP2v$93GVCle37u7MvJMFxQ==)
at System.Windows.Forms.ToolStripItem.HandleClick(EventArgs e)
at System.Windows.Forms.ToolStripItem.HandleMouseUp(MouseEventArgs e)
at System.Windows.Forms.ToolStripItem.FireEventInteractive(EventArgs e, ToolStripItemEventType met)
at System.Windows.Forms.ToolStripItem.FireEvent(EventArgs e, ToolStripItemEventType met)
at System.Windows.Forms.ToolStrip.OnMouseUp(MouseEventArgs mea)
at System.Windows.Forms.ToolStripDropDown.OnMouseUp(MouseEventArgs mea)
at System.Windows.Forms.Control.WmMouseUp(Message& m, MouseButtons button, Int32 clicks)
at System.Windows.Forms.Control.WndProc(Message& m)
at System.Windows.Forms.ScrollableControl.WndProc(Message& m)
at System.Windows.Forms.ToolStrip.WndProc(Message& m)
at System.Windows.Forms.ToolStripDropDown.WndProc(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m)
at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m)
at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)