I set up a custom type "products" and a custom taxonomy for it. I had some problem creating fields (they would not consistently be created) so I installed "Advanced Custom Fields" to handle the custom fields on the products. That worked nicely.
I imported 300+ products using the "CSV Importer" plugin. That also worked fine.
I installed "oik base plugin" and "oilk fields" so can view the products in tabulated form within a page. That all worked find and great too.
I'm telling you all this in case there are some interactions that you know about.
I came back to this the next day, and found the Products post type no longer appears in the admin menu. It did the day before, so I have no idea what happened. The post type is still there, as is the imported data, but I just cannot see it in the admin menu.
I have the post type set to "public", so it should be there, and it was the day before. I really cannot think what could have changed to make it disappear.
I've turned on all debugging options in WP and cannot see the slightest sign of a notice or warning when the pages load. What could have happened?