Some images went lost after I smushed, what can I do?

Hey folks,

When I installed WP Smush pro on my WP and smushed my pictures, some seem to went lost after the process. For example: I got a Rev.-Slider on my homepage, some preview Images are broken now and also some other preview images on the website are missing (Some categories e.g, but not all).

Any clue what I might do? i I like the plugin and think this may be resolved easily ????

this is the site i am talking about: cat-news.net
thx for help!! PS: I can grant access in not time if needed!!