Alright, I've solved the problem, and indeed it was caused by Roundcube. I performed a downgrade of Roundcube from version 1.6.6 to 1.6.0, and the issue was resolved.

Here's how I did it:
I navigated to the following path:

/usr/local/cpanel/base/3rdparty
and renamed the Roundcube folder to roundcube_bak. Then, I pulled files from another website for Roundcube version 1.6.0 and uploaded them to the same path on my server.

I use the Larry interface for my business email and it changed today to elastic is there any way to change this back to Larry??

Its the enigma plugin that comes with Roundcube but does need to be setup https://github.com/roundcube/roundcubemail/tree/634220623997a1f465e67391af48cd893706a355/plugins/enigma

Thanks for the insight. This comment made by this user on that thread was particularly interesting: https://support.cpanel.net/hc/en-us/community/posts/23150240197399/comments/23180533983767

Is it possible to keep the user guides / Help files updated - at least on the annual basis?

The v1.1 guide is too far from reality, thus almost useless and even misleading.