Hello,

First of all, check if you have activated any action after add to cart event: Theme Settings > Shop > Action after add to cart http://prntscr.com/jq6ave

If you want a sidebar appearing after you click add to cart in the header, check Woodmart > header builder > cart element http://prntscr.com/jq6bbw

If you have done all but still have the issue disable all the third parties plugins not related to the theme and check the issue again.

Best Regards