Hi @mehdinajaran
Do you remember making any changes before the issue started such as updating or installing any plugins?
This kind of problem is usually caused by a conflict with your theme or with another plugin. The best way to determine this is to:
- Temporarily switch your theme to Storefront
- Disable all plugins except for WooCommerce
- Repeat the action that is causing the problem
If you’re not seeing the same problem after completing the conflict test, then you know the problem was with the plugins and/or theme you deactivated. To figure out which plugin is causing the problem, reactivate your other plugins one by one, testing after each, until you find the one causing conflict. You can find a more detailed explanation on how to do a conflict test here.
You may test this out on a staging site using a plugin like WP Staging.
If the conflict test doesn’t lead to the cause of this unusual behavior, then please share a copy of your site’s System Status so we can get a better idea of your setup.
You can find it via WooCommerce > Status. Select “Get system report” and then “Copy for support”. Once you’ve done that, paste it here in your response.