Divi Builder crashing when trying to save on specific page

This is a strange one. I have this page:

https://ordainminister.com/psychological-support-resources/

If I try to edit the tabs section just to change the color of the tab backgrounds for active/inactive the builder refuses to save and say it failed, try again, blah blah. So I thought that there was a glitch in that specific page so I recreated it. That would be this url:

https://ordainminister.com/psychological-support/

You'll see it's pretty much identical with the exception I was able to change the tabs backgrounds. BUT, if you scroll to the bottom you'll see that the text in the right column of the last text area is missing. If I add that text then the builder won't save. Same problem I had with the original page except this page won't let me complete it and the other wouldn't let me change it.

The server is set up for maximum Divi compliance. Here's the major stats:

Max_execution_time: 90
max_input_time: 180
max_input_vars: 3000
memory_limit: 512M
post_max_size: 128M
upload_max_filesize: 64M

The Google developer's console shows this error when trying to save:

VM3550 jquery.js:4 POST https://xyz123456.com/wp-admin/admin-ajax.php 404
send@VM3550 jquery.js:4ajax@VM3550 jquery.js:4es@VM3588 bundle.js:2ol@VM3588 bundle.js:2(anonymous)@VM3588 bundle.js:2e._invokeCallback@VM3588 bundle.js:356e.dispatch@VM3588 bundle.js:356buttonClick@VM3588 bundle.js:2value@VM3588 bundle.js:9Gg@VM3569 react-dom.production.min.js:155Fg@VM3569 react-dom.production.min.js:13Ig@VM3569 react-dom.production.min.js:13be@VM3569 react-dom.production.min.js:15Jg@VM3569 react-dom.production.min.js:156Ic@VM3569 react-dom.production.min.js:15Kc@VM3569 react-dom.production.min.js:16hh@VM3569 react-dom.production.min.js:39mg@VM3569 react-dom.production.min.js:149se@VM3569 react-dom.production.min.js:23Yb@VM3569 react-dom.production.min.js:40og@VM3569 react-dom.production.min.js:150Te@VM3569 react-dom.production.min.js:40trigger@VM3388 jquery.js:3a.event.trigger@VM3389 jquery-migrate.min.js:2(anonymous)@VM3388 jquery.js:3each@VM3388 jquery.js:2each@VM3388 jquery.js:2trigger@VM3388 jquery.js:3(anonymous)@?et_fb=1&PageSpeed=off:21(anonymous)@VM3588 bundle.js:289dispatch@VM3388 jquery.js:3r.handle@VM3388 jquery.js:3

Basically the admin-ajax appears to be failing or having a conflict. I'm using Divi 4.0.5 which, according to their changelog, is supposed to work with Divi Ultimate.

Other pages haven't had the issue but they don't contain the same type of modules and content. So it's not clear IF they would/could/did crash when trying to save.

I've disabled ALL plugins and tested, same result. It doesn't appear to be plugin related but i'm not an expert.

Please advise. Thank you!