Ubuntu Mate UI graphics bug

I installed Ubuntu Mate on my son’s Toshiba Satellite laptop and got Audacity from the repo.
The laptop has an Intel 5500 motherboard graphics chip and also a Radeon R7M260 graphics auxiliary chip.
Audacity works but the buttons and the wave form graphics do not appear.
If you move the cursor over the wave form box it will show the underlying wave as you go.
I can see the places where the Start Play Rec buttons are and if clicked they work but they never appear.
This looks similar to the bug reported here:
https://forum.audacityteam.org/t/missing-toolbar-icons/49960/2

It is a new fresh Ubuntu Mate install with free drivers.
I afterwards tried installing the Radeon drivers but the problem persists.

Thanks
David

Please post a screenshot so that we can see what you mean.
(Instructions for how to attach an image to your forum post: https://forum.audacityteam.org/t/how-to-attach-files-to-forum-posts/24026/1)