With latest Emacs from trunk as of today, I cannot display the export
dispatch UI of Org.

Here is a minimal recipe:

emacs -Q
M-: (set-frame-font "Meslo LG M DZ 11") RET
C-x C-f ~/test.org RET
C-c C-e

Of course, you need this the Meslo font installed.  But maybe the
problem happens for other fonts as well.

I'm attaching a backtrace.