Turns out TERMINFO is not set in my environmental variables. A fix for now is to add this to my .zshrc file:
This doesn't explain why it is not set anymore, but it works for now. Thanks to @ThomasDickey for the help!
I am answering my own question as Fosforo inspired me to try a few things that solved the issue.
With your current suit of active programs, you cannot manipulate windows in xvfb using xdotool.
xdotool is still allowed to get information, for example, you can find the PID of your xterm window running the command:
DISPLAY=:10 xdotool search --name "xterm&...
Try using getwindowname to debug it.
xdotool search --onlyvisible --name 'TITLE_YOUR_WINDOW' getwindowname
and output it to a file.
Some basic window managers accept getwindowname but not getactivewindow.
The second option is to use a vncserver. It works perfectly fine for headless desktops doing automated stuff. being doing for years.