I managed to get the Powerline fonts working on my Windows 10 pc to use in WSL, particularly in the VS Code terminal window so I can use the Agnoster oh-my-zsh terminal theme. I set it all up and everything works - cool.
BUT when I shutdown my pc and restart it, the font no longer works in VS Code. However, it does still work in the ubuntu window. See ↓
https://i.sstatic.net/4UUT2.png -- Sorry, I don't have enough rep to post images :(
I noticed it is not installed in the settings > font window
But it is installed in the control panel fonts window.
Current workaround
I can get the font to work again if I reinstall the font, at which point Windows will prompt me that The font is already installed, do I want to reinstall?. Click yes.
At which point the font will appear in the fonts settings (Add fonts) window.
What is going wrong with the font installation? Reinstalling the font after every boot seems tedious... I suppose I can get a script to automate that on startup but I really want to get to the root cause.
EDIT
So I just found the fix - had to right click on the .ttf file and 🛡️Install for all users.
I don't know why installing it as the local user didn't work but hey ¯\_(ツ)_/¯
I found the answer to my own question...
Have to right click on the .ttf file and 🛡️Install for all users.
It seems that if the font is not listed in the Settings > Personalization > Fonts window, VS Code will not find it. Installing for all users makes the font persist there after reboot.