Group Navigation Banner "Blank"

One of our group navigation banners is "suddenly" blank. I'm sure the group owner did something, but I can't identify what was done to get the navigation banner to look or act this way. The settings are to inherit, and even when I change it to color and assign something dark I still get the same result. Any help debugging this is appreciated.

Below are images of the group and of our standard banner as a reference.

Standard set up/ group banner:

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