It’s ok that you see the backend messed up with 2.6.8 and latest Woocommerce. They have changed things in a backwards incompatible manner breaking this and apparently other plugins. You will need to upgrade the plugin in order to get it working correctly with modern Woocommerce versions.
It seems some error happened during the first plugin upgrade attempt what prevented the plugin from converting your rules to the new format. New rules format is required by the modern plugin versions.
Anyway, none of your existing rules are removed during upgrade. So you can try to upgrade again. Hopefully, that will go ok this time. If not, please copy/screenshot any errors you see during the update.
To trigger updating again:
1. Install the latest plugin version.
2. Close any dashboard tabs opened to make sure update won’t happen in the background, triggered by periodic ajax calls wordpress makes to the backend on admin pages.
3. Find an option called ‘woowbs_version’ in the wp_options table and change its value to ‘2.6.8’.
4. Open the plugin settings page.