I had a look on this issue and the problem is how you did the translation of the slug of the reviews CPT.
I believe that you used the field “Review post type slug” from Theme Settings -> Translations in order to add different slugs for each language?
The correct way with WPML is to leave the “Review post type slug” field empty for all the languages in Theme Settings (It is very important to be empty in every language in order to use the default “review” slug).
After that you go to WPML -> Settings -> Post Type Translation .
You find the “Reviews” and make it “Translatable – only show translated items”.
Under this option you’ll find another option called “Set different slugs in different languages for Reviews.”.
With this option you’ll be able to add different slugs for the CPT “Reviews”.
I tested it and it works just fine!