I use products variations on my site but eBay doesn’t allow variations in the selected category. How can I find out in which categories variations are allowed?

Unfortunately, eBay doesn't allow to list variable products in each category.

To learn more about variations and allowed categories you should visit this page: pages.ebay.com/help/sell/listing-variations.html. 

There you will find a link to eBay’s  look up table for categories allowing variations.