Hi there!
There are many different things that could be causing this issue.
It could be related to caching, either by your server or by a caching plugin on your site. You might want to try disabling any caching plugins and testing, or asking your hosting company about caching on your server.
It could also be caused by a conflict with either your theme, or with an active plugin on your site. To check for conflicts, please try temporarily switching your theme back to Storefront (https://woocommerce.com/products/storefront/) and disabling all plugins except for WooCommerce, then check to see if the issue is fixed. If it is, then you can switch your theme back and reactivate plugins one-by-one until you find the one that is causing the issue.
You can read about testing for conflicts in our documentation here:
https://docs.woocommerce.com/document/how-to-test-for-conflicts/
I hope that helps!