ajax pop up does not load contents

Hello I would like to report that after enabling your plugin, page loads very fast but when I click on a portfolio item to see more details in the ajax popup the first time loads correctly but when I try to click it again it doesn’t load the contents.

I disabled gzip compression and seems that the problem disappears.

I don’t know if it’s a bug or what, I felt obliged to report it.

site is http://www.computerman.gr

best regards

https://wordpress.org/plugins/wp-fastest-cache/