Xubuntu: Choosing Settings from Desktop causes flicker

I am using Xubutu beta 21.04 running has a Virtual machine under KVM. My host machine is a Linux Mint 20.1 on a Dell I5 with 8 GB RAM.

cat /etc/*release output:

DISTRIB_ID=Ubuntu
DISTRIB_RELEASE=21.04
DISTRIB_CODENAME=hirsute
DISTRIB_DESCRIPTION="Ubuntu Hirsute Hippo (development branch)"
NAME="Ubuntu"
VERSION="21.04 (Hirsute Hippo)"
ID=ubuntu
ID_LIKE=debian
PRETTY_NAME="Ubuntu Hirsute Hippo (development branch)"
VERSION_ID="21.04"
HOME_URL="https://www.ubuntu.com/"
SUPPORT_URL="https://help.ubuntu.com/"
BUG_REPORT_URL="https://bugs.launchpad.net/ubuntu/"
PRIVACY_POLICY_URL="https://www.ubuntu.com/legal/terms-and-policies/privacy-policy"
VERSION_CODENAME=hirsute
UBUNTU_CODENAME=hirsute

When I right click the desktop and choose Desktop Settings, most of the time (but not always), the popup menu flickers many times before the Desktop screen appears.

I most often see this flicker when the desktop has no other open windows.