Built linuxcnc, ran tests, but when it runs, graphics are really bonkers

I don't know if anyone can help me with this issue. I upgraded to Debian Buster from Stretch, and everything seems to work find, except that I just built linuxcnc from sources, and although all the tests pass, Axis has real issues. Almost all of its screen rendering is corrupt. See this movie I shot of my screen:

share.getcloudapp.com/nOun0lZ4

I'm hoping this is an issue confined to linuxcnc, rather than my OS update.

Any advice on how to fix this (short of installing a whole new OS from the ISO) is much appreciated.

SOLVED. But not really

I finally found the buildbot page, which detailed what the sources.list change needs to be to get the 2.9 packages. I updated that, then was able to install the latest 2.9 via apt install.

Unfortunately, the move to Buster seems to have made my machine even more unstable than it was under Stretch. I'm still experiencing this problem of the desktop freezing up completely, even though the machine remains accessible via ssh. It was recommended to me to upgrade to Buster, but that was a huge mistake. I hope I can restore the backup I had.