Thanks to @HansPassant for the advice regarding the font cache.
What I did was:
- Stopped WPF Font Cache services
- Deleted all the font cache "log" files from the locations listed in the Service list
- Rebooted.
I am not sure exactly what caused this as I try to install some new fonts but realized IT hadn't given me permission to the folder, but I believe this strange issue arose from the last Windows update.
As it turns out, stopping the WPF font cache services can also mitigate the "glitchiness" of Visual Studio that some people experience. Hope this helps others :)