White box around gnome-terminal menu

[Aptivi]

Whether the menu is open to zoom in, go to full screen, etc., the menu spawns correctly with all of the buttons properly rendered, but there is a white box behind the menu.

To elaborate, I have a fresh install copy of Ubuntu 20.04 development branch on VirtualBox with the standard VirtualBox graphics driver (pre-installed) to enable Mouse Integration. Everything renders fine, except that if I have to open a menu to edit the preferences, the white box behind the menu appears, but only in the right and the bottom edges. If I click on the white box on either edge, the menu closes down. If I hover over it, it shows the normal cursor, not the text selection cursor.

The box does not have the curved corners unlike the rendered main menu form.

gnome-terminal version:

gnome-terminal:
  Installed: 3.34.2-1ubuntu1
  Candidate: 3.34.2-1ubuntu1
  Version table:
 *** 3.34.2-1ubuntu1 500
        500 http://sy.archive.ubuntu.com/ubuntu focal/main amd64 Packages
        100 /var/lib/dpkg/status

Ubuntu version:

Description: Ubuntu Focal Fossa (development branch)
Release: 20.04

ProblemType: Bug
DistroRelease: Ubuntu 20.04
Package: gnome-terminal 3.34.2-1ubuntu1
ProcVersionSignature: Ubuntu 5.3.0-18.19-generic 5.3.1
Uname: Linux 5.3.0-18-generic x86_64
NonfreeKernelModules: zfs zunicode zavl icp zcommon znvpair
ApportVersion: 2.20.11-0ubuntu9
Architecture: amd64
CurrentDesktop: ubuntu:GNOME
Date: Fri Nov 15 21:11:38 2019
InstallationDate: Installed on 2019-10-21 (25 days ago)
InstallationMedia: Ubuntu 20.04 LTS "Focal Fossa" - Alpha amd64 (20191020)
SourcePackage: gnome-terminal
UpgradeStatus: No upgrade log present (probably fresh install)

[Launchpad Janitor (janitor)]

Status changed to 'Confirmed' because the bug affects multiple users.