Google Tag Manager Causing White Screen

Hey. I got the weirdest error and not sure what to do so coming to you guys about this since Google of all places is no help.

Basically, I got an email from our SEO person who said that our site died when he added the Google Tag Manager Code. He was using the WP Google Tag Manager plugin.

He deactivated all plugins to test but nothing resolved the error. (Note: this was done on the live site, and because of the site, the 10 min. or so the site was down caused about $2k. There is a testing environment for this site now, but whew...)

To test, I deleted this plugin and added the google code directly to the header.php file. (Site is using the Avada theme from ThemeForest) I added the code via directions from google. "Place directly after the body tag". I uploaded and I saw the same issue. (Thankfully my created downtime was a few seconds)

Results: Page loads for a split second then turns to a white-screen.

Quick Solution Attempted: I commented out the tag manager code and the site worked fine. When uncommented the site would not load.

So I'm asking you all here to help since it seems such a bespoke problem.

Quick Rundown: Added google tag manager script to header.php broke site. uncommented script site works again. no plugin conflicts.

Thanks