HUD not working for Firefox, LibreOffice & others in 18.04

[TenLeftFingers]

In 16.04, invoking the HUD allowed commands to be typed which would produce a list to choose from. In 18.04, pressing ALT does show the empty HUD - but typing commands doesn't populate a list for some applications. I upgraded from 16.04 to 18.04.

Not working:
Firefox, LibreOffice, Audacity (even with pasuspender)

Working:
Gedit

Other apps work, but don't display comprehensive menus like in 16.04. Eg, gnome-terminal only shows a Terminal menu in the menu bar rather than File, Edit, View etc that was present on 16.04. Other examples of these are Baobab, Nautilus.

It didn't affect upgraders until recently according to two commenters here: https://askubuntu.com/questions/1035794/hud-doesnt-show-menu-entries-on-18-04-unity

ProblemType: Bug
DistroRelease: Ubuntu 17.10
Package: hud 14.10+17.10.20170619-0ubuntu1
ProcVersionSignature: Ubuntu 4.13.0-41.46-generic 4.13.16
Uname: Linux 4.13.0-41-generic x86_64
NonfreeKernelModules: wl
ApportVersion: 2.20.7-0ubuntu3.7
Architecture: amd64
Date: Mon May 14 18:47:52 2018
InstallationDate: Installed on 2016-02-11 (823 days ago)
InstallationMedia: Ubuntu 16.04 LTS "Xenial Xerus" - Release amd64 (20160420.1)
ProcEnviron:
 LANGUAGE=en_IE:en
 TERM=screen-256color
 PATH=(custom, no user)
 LANG=en_IE.UTF-8
 SHELL=/bin/bash
SourcePackage: hud
UpgradeStatus: Upgraded to artful on 2018-05-13 (1 days ago)

[TenLeftFingers (tenleftfingers)]

Updated to 18.04 from 17.10. Same issue.