Hello,
I suppose you missed how that option work.
If you set custom order here https://prnt.sc/1ls9k59 then you are able to change the order of the terms here https://gyazo.com/15d84f43de43ceaad409ee9c04508e6a and it will be changed on the product page https://gyazo.com/102b1fa1e9797c9391f9ea2d2ae02ed2
Everything works fine according to the option description (Determines the sort order of the terms on the frontend shop product pages. If using custom ordering, you can drag and drop the terms in this attribute.).
Regards