This is reproducible.  No external monitor attached.

Top panel is set to autohide.  Compositor is on with alpha.

I go to my name menu and choose lock screen.

I type my password and unlock the screen.

Panel is now stuck open and will not hide.

I moved my mouse up at the last second before lock screen engaged,
I don't know if that's absolutely necessary.

This is inconvenient because maximizing windows still maximizes
them to the area they would be if the panel was hidden.  So then
there is no way to access the title bar of the maximized window.

How do I use xfce4-panel-dbg?

Thank you.

Mark

An easy interim fix would be to HUP the panel when unlocking the screen.

This seems to reset the panel so it autohides again.

That does not really fix the bug though.