Just adding some products a few minutes ago, and I seem to be missing the category selection option for the product.
It's just not there!
There are categories, set to display, but they don't list any products. (categories do list products, I had a filter on for some reason!)
When the existing products were created, they were put into various categories.
Also, the options for stock status, quantity and tax class have all disappeard too - not sure if it's related, if not I'll ask a new question for those.
Running Magento 2.1.7. I've beens earching for a good while now, but can't find anything relevant to help (most issues involving categories are about not showing on the front end).