Black screen after logging in via sddm - FreeBSD 14.1, Xfce 4.18_1

I just upgraded to FreeBSD 14.1 and ran into a problem with Xfce 4.18_1 starting after logging in via the sddm login screen. The display would just go black. The mouse cursor is still visible and I can move it around.

I have narrowed it down to the following:

(1) I removed my Xfce config under ~/.config/xfce4, logged in, and Xfce started ok.

(2) I replaced my Xfce config under ~/.config/xfce4, and after much trial and error, found that ALL of my config works EXCEPT ~/.config/xfce4/xfconf/xfce-perchannel-xml/xfwm4.xml. If I remove that file and only that file, and then login, Xfce starts ok.

(3) I then log out of Xfce4 back to the sddm login screen, and try to login again.

(4) I get the same black screen. Note that I did NOT change the config files.

(5) I restart X, and before I log in, I remove the xfwm4.xml file that Xfce created. I then log in and Xfce starts ok.

(6) I log out, remove the xfwm4.xml file, log in, and Xfce starts ok.

(7) I can repeat (6) indefinitely and Xfce always starts ok. But if I do not remove the xfwm4.xml file, Xfce does not start ok. The screen just goes black after logging in.

I searched the issues list and didn't find anything like this. Apologies if I missed something.