Both me and my wife have iPhone X and both with cases and use the wireless charger with no problems. I use a very thin case, I think is the thinnest in the market but my wife uses a regular case that's very protective and still works. These are the cases we have:
https://www.itslaut.com/collections/iphone-x-case-collection/products/slimskin-for-iphone-x
https://www.bestbuy.com/site/incipi...iphone-x-and-xs-clear/6103724.p?skuId=6103724
Hope it helps!