when I ‘customize’ from the theme, I get the left hand side WP column…slowly…and the annoying spinning dot…for hours.
1. disabled all caches, purged all db
2. switched to another GPtheme
3. tried IE/Chrome/FF, all the same issue.
4. deleted all browser history.
If that doesn’t work, deactivate all non-GP related plugins and see if the issue persists. If not, activate them one by one until the problem plugin is found.