Hi afshin,
Thank you for reporting this.
Could you make sure that you have the latest theme version and that all recommended plugins are up-to-date? Finally, you could also consider clearing all activated caching system as well as your browser cache before investigating any further. If you want to read more on what browser cache is and how to clear it, here is an article that might help you: How to Clear Internet Cache in Every Major Browser.
Then, if this issue still occurs, can you please send us the url of the page so we can inspect this issue?
Thank you.