XF 2.1 Can't update Messages options in Admin

I am able to change all my forum settings/options with the exception of anything in the Messages section. I get the OOPS! Error.

In the browser console this is what I am seeing. Can someone point me in the right direction?? I have no idea what could be going on.

core-compiled.js?_v=95aae0b8:45 PHP: <!DOCTYPE HTML PUBLIC "-//IETF//DTD HTML 2.0//EN">
<title>500 Internal Server Error</title>
<h1>Internal Server Error</h1>
<p>The server encountered an internal error or
misconfiguration and was unable to complete
your request.</p>
<p>Please contact the server administrator at
webmaster@theotterhand.com to inform them of the time this error occurred,
and the actions you performed just before this error.</p>
<p>More information about this error may be available
in the server error log.</p>

defaultAjaxError @ core-compiled.js?_v=95aae0b8:45
/forum/admin.php?options/update:1 Failed to load resource: the server responded with a status of 418 ()
Hello, if you have installed some add-ons you can disable them one by one to see if the error come back

Regards, SyTry
No add ons installed. It is a fresh install and I noticed this during setup of the forum.

This is the only area I can not update. None of the other options are having saving issues.

The permissions are all set properly for all files and folders as well. I have also checked with ModSecurity and all seems fine there as well.
I went to my hosting service and had to disable their enhanced security for the domain. They’re not responsive as far as what impact that has on server operations for the forum software.

With enhanced security deactivated it worked. I’m just wondering why the messages option is the only area where there was a problem.

I was trying to increase message length.

now that the option is saved, I’m looking to re-enable the security, but don’t want to find more errors within the front end of the software. 😬