The word “Having” gives Error 403

Unknown how long the issue has been present, as the actions to recreate had not occurred for a very long time.

Inherited a wordpress site for a customer from someone “who was doing it as a hobby” and whilst it isn’t in the best shape css-wise, it does what they need it to

WordPress 5.1.1 running Elle theme. Using Genesis 2.8.1.
PHP 5.6 (tried 7.0 too) on apache w/litespeed (not enabled/caching) on cloudlinux 7.6
Page builder 2.10.2
Widgets bundle 1.15.3

Whilst it’s unknown if it happened prior to WordPress 5 (we created the pages a few years ago and never touched since), the PHP version was updated when WP was, page builder and widgets bundle too – still it occurs.

I’ve disabled all plugins – no difference (disabling page builder obviously fixed it, but that’s not the point)

I then looked at recreating the widgets – maybe something was corrupted in them?.. This is when I narrowed down a sentence “.. and having fun..” and found that the inclusion of the word “having” will result in a 403 on trying to preview a SiteOrigin Editor widget, results in a 403 and no saving upon attempting to save a widget, and if you try to edit a widget containing the word, error 403. Try to save a page with the word in an existing widget from before – error 403.

This happens only when editing the pages/widgets, the front end and the existing mentions of “having” all display fine to the visitor.

Furthermore, characters before “having” such as “behaving” trigger this too however, having-comma “having, ” does not trigger it

having – 403
having, – 200
behaving – 403
behaving, – 200
havin – 200
aving – 200
have – 200

To replicate:
goto Posts – Edit one with siteorigin editor – add row – add siteorigin editor widget – type ‘having’ – click preview .. you get 403.
-or-
try to edit an existing siteorigin editor widget that has the word in.

Please could someone kindly offer any advice/assistance?

Thanks,
Matt