Rendering stuck issue on Fixer theme

Hello. This is my 2nd attempt to create this and I lost all of my previous detailed info.

I am experiencing the rendering issue when I click the Upfront button. It gets stuck at 43%. I've tried it on Chrome and Firefox as well as had someone in a different location try Chrome and Firefox. I've read some other threads and have already tried the following tips.

Cleared the cache on Chrome and Firefox.
Uploaded a different main.js from one of the threads (provided the link in the 1st attempt and can't find it now)
Reset the Upfront cache
Deactivated all of the plugins
Updated my .htaccess with:
<IfModule mod_security.c>
SecFilterRemove 00318

Updated my wp_config.php with:

I switched to the Gillie theme and that allowed me to render to 100%. However, when I switched it back to Fixer, it was stuck at 42% render again.

Any thought super hereos?