I know there has already been such a topic here. But this clearly requires an urgent fix. Vendors cannot add products after purchasing any plan. The permissions are set, but the vendor’s Add Product menu appears and disappears.
Hi Victor, please make sure you have added both Product Releated Capability as well as Allowed product types, only then vendor can add product.
For better explanation please refer to this image https://scrnli.com/ZjwB62id0Nm0na
It seems like there is some plugin/theme conflict. Just to be sure, disable all the plugins except WooCommerce and WCMp and check again.
If the issue still exists, please switch to some default theme such as Twenty Sixteen and check again.
Please do keep us posted so we can help you out.