Hello,
1) I can’t login to your Dashboard to check what you are talking about because get error message http://prntscr.com/gpdn2s
Do you have this problem with our theme only? Have you tried to add the page and save menu with default WordPress theme? Do you get the same issue?
2) Theme can’t affect thumbnails. Did you use any third-party plugins? What actions did you do before this happened? Is everything ok now?
3) Do you use the third-party plugin to add meta description? Which one?
Regards