When I try to modify the tipping banner, everything works, except for the big background image. I changed it numerous times now, but every time I get the grey image with the triangles and hearts back.
Updating the image and preview shows fine, but after the save… it has disappeared again.
In my developer console I see one error… I get an HTTP 500 on a PUT to:
Request URL: https://publishers.basicattentiontoken.org/publishers/08c079c4-xxxx-13c8c01fa7a3/site_banners/48b7bc6c-xxxx-e4c23b68d6b1
I replaced some character with x-es here.
Thanks for the report. I will bring this up to the publishers app team and get back to you when I hear more!
@Leviter, it looks like the source of error might be the filesize of the image you’re trying to upload (i.e., too large).
See if you can try reducing the dimensions of the image, or saving it in a different format or quality level. (For example, .png’s tend to be large, while .jpg’s tend to be significantly smaller in filesize, holding perceived quality and dimensions constant.)
If this does not solve the problem or, given the existing file size, cannot plausibly be the problem, let me know!
Got it to work with your hints.
It seems to be related to the dimensions of the image and not directly to the size of the file. I tried and fiddled around with this. Same image with less quality (going below 100KB) did not fix it. Changing the width from 1100px to 800px (not changing quality) did fix it.
It would be nice to mention such limits if they are known. 
Thanks for your support.
Hey there!
We filed an issue for this on our Github. Now that it’s been logged I anticipate us addressing it within the next few months.