I'm using a Thinkpad E590 (i7-8565U with Radeon RX 550X GPU). Windows 10 & Labview 2019 (19.0f2).
In the end, I discovered google icons (https://fonts.google.com/icons) and have been using that to create my own buttons. I actually like the results more than the DMC content, so I don't think I will spend any more time trying to solve this. Still a weird problem though!
Anyway, I'll follow up here if I find anything useful. Thanks for the help and good luck 🙂