Unable to change namespace avatar in Galaxy NG

I am trying to update the avatar image of my namespace (and consequently collection), which is currently using the profile picture I had on GitHub when I first logged in. Updating it there was not automatically reflected on Galaxy. However, while entering a new URL under “Logo URL” in the namespace settings does change the preview image, it is not kept upon clicking save.

Are there any particular requirements for the image hosted at the entered URL for Galaxy to properly store it? I have tried the direct URLs of both my GitHub avatar as well as Gravatar, and neither took.

Notably, there is no error message upon saving.