I experience today lots of troubles with WP Smush Pro.
I've installed it on a website running for 2 weeks without any issue.
Today, I Smashed all media (about 1500). And it breaks my htaccess file.
I repaired the htaccess file, site is running back. I start again Smush Pro and it breaks the website again.
3 times, each time after starting Compression, it breaks my htaccess file.
Do you think it could be an incompatibility between WP Smash PRO and iThemes security ?