Hello,

You need to increase PHP max input vars limit parameter, now it is 1000. 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

I will try to upload demo without the plugins, I see the demo has not been uploaded.

Best Regards