Black screen/tiny window/crash to restart

I recently bought BF1 on Steam on a sale.  When it boots up, it usually goes black screen, then loads in a tiny window top left.   The game settings say full screen but it’s not.  If I change settings to full screen or hit Alt Enter, it usually goes full black screen with DisplayPort not found error or reverts.  It rarely works and the game can be played normal once out of 20 tries.  The most common outcome is the DisplayPort permanently shuts off, no alt tab or alt ctrl del works, forcing a hard reboot.  Occasionally I get a DirectX error.  I have tried both DX11 & 12. DX 12 won’t load at all. I’m running a 4070 in 1440p ultra settings, no hdr with up to date drivers & windows update. 10 year old rog monitor.  This is the only game in years to do this.   Please help, considering refund because of the forced shutdowns but would prefer to actually play.