Site Logo Not Updating

I am trying to update the logo in the top left corner of the site. I have tried the straight forward logo replacement in the Site Identity section of the Theme editor which has led to two issues. Firstly, I can’t seem to figure out the image size to make it look good. Secondly, and more importantly, it doesn’t seem to matter what I do in terms of cache clearing, etc., whatever logo I change to doesn’t publish. I can see it in the preview window, but doesn’t show up on the published site.

I also tried directly editing the image that I thought the theme was already using, and the image edit saved, but the result is the same as above. Please help!

The page I need help with: [log in to see the link]