Due to the variety of themes, it can happen that you don’t see your age gate immediately after you saved the settings. This happens because the theme is using a high Z-Index value to manage its layouts. It’s often used to keep the navigation on front of the rest of the layout.
How to fix:
Go to WooCommerce->Agy->Design and take a look at the “Content Box” section. You will find a setting called “Z-Index”. Increase the value, save the settings and check the frontend of your WooCommerce store. If you still do not see the age gate you will most likely increase the value even further.
Keep in mind that you may also need to increase the Z-Index value of the background to make it visible within your theme. You can follow the exact same steps, but this time you increase the value within the “Background” section: