I can see your front page, thank you.
Your theme is The7 version 3.3.1 but the current version is 4.4.5. See the changelog. There are many fixes in the later version, including compatibility with later WordPress and WooCommerce versions of which you have the latest. Hopefully one of the fixes will be for your problem.
Consider updating your theme as the next step. Best to take a backup first. Updating can bring its own problems. Consider asking The7 support whether there is a recommended way of doing it, or a guide, especially as you would be going from 3.x to 4.x. For example, you may need your original purchase code to authorise the update.
https://themeforest.net/item/the7-responsive-multipurpose-wordpress-theme/5556590
If you don’t update your theme you would have to wind back WP and WC to the versions which were current when 3.3.1 was released to get it all to work in harmony. However, winding back is definitely not a good idea.
There are further debug steps if updating your theme does not resolve the problem.