This is a huge problem and it needs to be resolved.
I agree that it’s a “huge problem” that needs to be resolved, and immediately.
Except this “hamburger” mobile menu is a feature that came with your theme, not WordPress. And the solution needs to come from your theme, not WordPress.
Probably your first step should be to upgrade your theme. You’re running version 3.4.1, but the latest version (as of now) is 3.4.4. You also want to upgrade all plugins that were installed along with the theme, as is common with ThemeForest themes.
If after that you still have a problem, please contact your theme’s developer for help, as yours is a commercial theme. We don’t have access to commercial products here at www.remarpro.com, making it impossible for us to help you troubleshoot the issue and find a fix.
Please see: https://themeforest.net/item/architecturer-interior-design-architecture-wordpress/22544684/support
… but it seems this has been a problem with Word Press for more than a year.
No, it’s not really a “problem” with WordPress per se. Rather, what is happening is that WordPress changes something, which causes themes and plugins to break. As software under active development, this is bound to happen. It’s the duty of theme and plugin authors to follow the latest changes in the mothership (WordPress), and adapt their own products accordingly. So the “problem” you mention is really a problem with those themes and plugins that haven’t been updated to work with the changes in the latest versions of WordPress yet (and in some cases, site owners who haven’t installed the latest updated versions of their themes and plugins).