Rules disappearing

I’m using: Mesmerize PRO theme, Version: 1.6.106; WordPress Version 5.0.3 and
Real-Time Find and Replace Version 3.9.
Whenever I add a new rule and hit the “Update Settings” button, the rule just disappears :/

I also use the following plug-ins Contact Form 7,
Google Analytics Dashboard for WP (GADWP), Imagify,
Lazy Load by WP Rocket, Mesmerize Companion and WP Fastest Cache.

Thank you very much!