The following was shared by a client having problems with uploads in JReviews not working:
Never disable all rules !! This could cause serious security issues!
The easiest way to disable individual mod_security rules if you are using cPanel is to install ConfigServer ModSecurity Control and use it to disable individual mod_security rules by ID or via a specific directory.
Otherwise you will need to review and edit specific Apache server files as follows: (Windows Web Server not addressed here)
The mod_security ID's I whitelisted for JReviews Joomla are: