Hello,
Please deactivate all the plugins not related to the theme, and switch to the parent them if you are running the child one and check again.
This issue may be connected to the PHP max input vars limit parameter in your web server configuration. You can check the current value for this parameter in your Dashboard -> WooCommerce -> System status. Usually, this parameter is not allowed to be changed on shared hostings so you will need to contact your server providers and ask to increase this limit. Recommended value for this is 5000
Best Regards
.
