Pressing Alt+<letter> accelerators do not bring up the menu

[Dan Dascalescu]

If I press and hold Alt, the accelerators for the menu bar (F&ile, E&dit, S&earch, T&erminal, Tab&s, H&elp) become underlined, but pressing the F/E/S/T/b/H key does not bring up the pull-down menu.

ProblemType: Bug
DistroRelease: Ubuntu 18.04
Package: gnome-terminal 3.28.2-1ubuntu1~18.04.1
ProcVersionSignature: Ubuntu 4.15.0-45.48-generic 4.15.18
Uname: Linux 4.15.0-45-generic x86_64
ApportVersion: 2.20.9-0ubuntu7.5
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Sun Feb 10 01:22:49 2019
ExecutablePath: /usr/lib/gnome-terminal/gnome-terminal-server
InstallationDate: Installed on 2018-12-31 (41 days ago)
InstallationMedia: Ubuntu 18.04.1 LTS "Bionic Beaver" - Release amd64 (20180725)
ProcEnviron:
 LANG=en_US.UTF-8
 PATH=(custom, no user)
 SHELL=/bin/bash
 XDG_RUNTIME_DIR=<set>
SourcePackage: gnome-terminal
UpgradeStatus: No upgrade log present (probably fresh install)