Custom Object Table Not Rendering Causes Velocity to Fail?

Hello all!
Have a ticket in with Support but curious on any thoughts on this strange situation. We've got an email that pulls in custom object record data for a certain type of account and had an instance where someone met the criteria (Smart List-wise and Velocity-wise) to receive the email BUT the script output table did not appear.

Here's where it gets weird - initially when I pulled up the object in the database in Edge and Chrome, the object loads but after the first 3 entries it looks like this:
MicrosoftTeams-image.png
The page then stalls and eventually crashes without loading. This Lead should have about 13-15 records so it's obviously not loading them in.

My initial Support response was that it was possible a cache/cookie issue and when I open that Lead in an incognito window it loads as it should.

What I'm confused by is when I do a specific "Preview by List" and replicate the list and Velocity parameters - why does my Velocity script seem to fail when previewing in standard Edge or Chrome but then it works fine and displays the table within the email in an incognito window?

Guess I'm confused why what seems to be a UI bug would cause the actual table load to fail in the email?

Note: It's (as far as I am aware) not a Velocity issue as the script works perfectly with other test cases.