I've been getting console errors on editing experiences, even newly created activities. Trying different browsers has helped previously, although I didn't check the console then. Clearing my cache seems to get it to work once, but once I save the content or go next and try to go back it breaks again. This happens on Edge, Chrome and Opera. See below screenshot.
Looks like website loaded through VEC have "HTTP" content, thus browser throws these errors and stops loading the content. Try enabling the "Load Mixed Content" setting in the Target setup screen.