I was able to get my header image squared away on my site (mission.wnccumc.org) using this information. That was helpful.
I was the first to mention these problems in the forum and I have still been unable to get the customize menu to load on 3 of 4 sites using Catchbox.
I updated to 4.4.2 on two of the 4 sites…and Customize is working on just 1 of those sites (the same one that initially loaded). The two sites are almost identical with plugins, and I tried to troubleshoot by deactivating plugins on the non working one (mission.wnccumc.org)–still could not get customizer to load.
I am waiting to update to 4.4.2 on the two other sites until you work on the fix.
Definitely some issues in the update and WP 4.5