Why is iTunes displaying random junk characters when I try to verify my billing information? I get garbled/garbage characters (weird font?) when I try to manage payment methods (I can't get past this screen to purchase a song*):



I also got this screen at one point trying to open an apple music link:



Using latest iTunes app from Microsoft store on Windows 10.

"For you" | "Try it now" also shows junk.

(*) Eventually I was able to purchase a song by guessing what the various fields/buttons were supposed to be. But obviously something very wrong. And yes, have rebooted etc. etc.

At least one other user has reported this: https://discussions.apple.com/thread/8066958, however the suggestion (starting iTunes in safe mode) didn't help.
Found the answer: delete any font on your system based on "Helvetica"!
Definitely confirmed this caused the issue - moved HelveticaNeue_0.ttf from the Fonts directory, everything displayed fine, moved it back, display messed up again.