Strange problem - Laptop, lid closed, Firefox window is blank

LMI Pro. Freshly installed on new company laptop (ThinkPad).

I have the display / power settings set so that closing the lid does nothing.

Not connected to a docking station.

When I close the lid, most things work exactly as they do with the lid open, but Firefox displays as a blank (white) window.  If I click where button/links are, the page responds (but still blank).  Things like the menu buttons, I found the View button and the menu displays just fine.  I selected to have Bookmarks as a Sidebar. Everything is still blank.  Find the View button again, and Bookmarks is now checked in Sidebar (as it should be).  I can close Firefox by clicking where the Close button should be.

This does not happen when I use Internet Explorer (or Edge), or Chrome, and I can also open other programs (Windows Explorer, settings, Word, etc.).

The reason that I said "most things work exactly" as with the lid open is that there is a slight difference in the display when the lid is closed.  For one thing, when the lid is closed, and I click the Windows (start) icon, name tags for the Power, Settings,  Pictures, Documents show up as I move the mouse over them, and they those tags get stuck in the display.  And, the programs (not pinned) have tiny icons when the lid is closed, and normal sized icons when the lid is open.  Also, if I go to Settings and choose an option that requires the window to scroll - it won't.  The scroll bar appears, and you can move the scroll bar, but the window itself does not change.

I don't have much software install on this yet, so I can't tell if there are other differences.

I saw some other thread that talked about the display accelarator - did that, no change.

The laptop was defaulted to a zoom of 125% scalling (recommended), I changed it to 100% - no change.

I wonder if it has something to do with the laptop thinking it is docked when the lid closes?  But I can't find settings in Windows for this.

I want to be able to close this up and use exclusively by remote, and not be distracted by the monitor.  I guess for now I'll just set the display brightness all the down.