TopMenu Panel Applet not behaving consistantly

I think this may be a GTK/TopMenu issue but am unsure where to go for assistance.

TopMenu works as I would expect when using programs such as Terminal/Evolution/Pluma but yet when using Firefox or Thunderbird there is just a blank space where the menu should be.

I’ve seen screenshots that show the menu’s in this applications appearing as they should be. Does anyone have any thoughts on what I am missing to get the expected behavior?

Hi @VinceN,

have you tried changing your software sources download location and updating again?:

You can also try the following terminal command (Ctrl + Alt + t) and restart if anything updates!:

sudo apt-get update && sudo apt-get dist-upgrade -f