I went to the C++ site and tried to change my font:
![Screen Shot 2020-02-24 at 11.27.31 PM.png](/image?hash=ce4a5fb2d50921714fef7dec840a07374283e8d7220dd557411808cd7c66b267)
After I clicked the "save" button the page refreshed, and I saw:
![Screen Shot 2020-02-24 at 11.27.51 PM.png](/image?hash=244153382dc6810df5980746958273c53cb1dc0b9c3be5a98bb386a017c216b5)
I first noticed this problem on Code Golf, and tried another site to see if it's site-specific, since Code Golf also only offers one font:
![Screen Shot 2020-02-24 at 11.30.23 PM.png](/image?hash=1c9083a0a39ec4a8665fbec7633a7062a3025b55f3c38fc52521322b118dc348)
Thanks, this is now fixed!
In the end it was easy to repro with a new account — as it only affected font changes on communities where you haven't yet posted or commented (or linked your SE account).