Great question — answering as the UphillTech team:
This could be a theme or plug-in conflict. In the first instance, check your theme for WooCommerce compatibility. If not sure, try with a different theme. If that works, you will either need to switch themes or contact the theme developer support. If if is not a theme conflict, disable ALL plug-ins (other than WooCommerce) and try. If that works, try re-enabling them one by one to identify the offending plug-in (and then remove + replace it with another one that doesn't conflict). If that doesn't work, (deactivate and) delete the WooCommerce plug-in and then re-install it. Hope one of the above fixes your problem. (You can try the above methods in any order.)
Full answer by Open Source Training Rajkot: https://stackoverflow.stackexchange.com/a/39804340 (CC BY-SA 3.0).
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