I have been using Creator to make Portals recently. Yesterday, I created a new portal and noticed that the page customization editor ("Open Builder") was different. Using the new page builder, I was able to customize and add an image to the various sign in, password, etc. pages. The image showed correctly in the page builder screen. However, the all of the actual web pages displayed the "default" image. If I opened the image in a new tab, it was not the file I had added in the page builder.
Also I encountered similar issues adding a favicon to the new portal. Creator allowed me to upload an icon, and the icon seemed to have uploaded successfully. However, the favicon was not displayed on the actual portal pages. Each page still had the default Creator favicon in the browser tabs.

I tested with Firefox and Chrome. I cleared my cache multiple times. The image and favicon never displayed.

That was all yesterday, June 1.

I logged into Creator today and the Portal page builder is completely black. It will not allow me to edit my portal pages created yesterday.

A portal I had created prior to June 1 still works properly, so my issues seem to be related to some update on or around June 1.