a11y does not work with the bubblewrap sandbox enabled, at least not on Fedora. Carlos Garcia reports it is working on Debian. One possible difference is dbus-broker vs. dbus-daemon. It's hard to think of what else might matter.
<rdar://problem/80103034>
Amazingly, it somehow works in Geary with WEBKIT_FORCE_SANDBOX=1, but not in Epiphany nor in MiniBrowser....
Possibly fixed by r289369? Need to check....
Is this still happening?
Nope, this seems to be fixed! Yay.