Qt GUI Dialogs Intermittently Rendered As Static within Docker

Question

I am having an issue where some Qt GUI menu items/dialog windows are intermittently rendered as black, or static, within a docker container. I am running an ubuntu 20.04 docker container on ubuntu 20.04 (preparing for deployment to other operating systems such as red hat linux), with Qt 5.9.5. The issue does not occur when I run the Qt GUI natively, only within docker.

Here is a screenshot of what the menus look like when they are rendered incorrectly:

This occurs seemingly randomly on different menu items and dialog windows at different times. Sometimes it will appear on a dialog, then I click around in the GUI, do other stuff, come back to the dialog, and it works correctly. I cannot discern a pattern for the items on which it occurs.

The issue appears to be similar (or possibly identical) to the issues listed here:

Qt5 Docker GUI occasionally rendering dropdown lists as noise

Qt app UI elements randomly rendered as blank/black in Docker

However, I have tried all the proposed solutions, and none have solved the problem. I have tried:

• Adding export QT_GRAPHICSSYSTEM="native" in my docker entrypoint.sh file

• Adding export QT_QPA_PLATFORM=offscreen in my docker entrypoint.sh file

• Adding --shm-size 128M parameter to docker run command, also tried 256M

• Adding --ipc host parameter to docker run command

Any other ideas?