Works on Subdomain but Not Live Domain

Created a subdomain with identical copy of live site. All plugins were imported and are up to date and compatible. When I Regenerate Thumbnails individually on the subdomain (haven’t tried bulk regenerate), everything works great. When I Regenerate Thumbnails on any one image on the live site, it doesn’t do or complete the request. It displays Regenerating Thumbnails but the scrolling little “rectangles” in front of the text just keep scrolling. Subdomain updates take 3-5 seconds. I’ve let the main site run for half an hour or more.

Site is hosted on GoDaddy, Linux with cPanel if that makes a difference here. It’s not GoDaddy WordPress hosting, but a site that was developed in WordPress that GoDaddy hosts. ThemeNectar Salient theme.

It feels like I need to refresh or clear something for the Regenerate Thumbnails to work on the domain, but I don’t know where.

Thanks for your assistance!