I haven't sold on eBay in a few years so am maybe a little rusty. I created a new listing today and have the free shipping option selected. However when I look at the preview of my listing, it says "calculate" under the shipping cost section. Also I have it set to USPS Priority Mail. It had the default shipping option set to USPS Ground Advantage. I've tried looking up answers to this questions but they are all a few years out of date now. I tried the online...

Change your shipping settings from Calculated to Flat, then check the free shipping box.

Free shipping not displaying in listing | Shipping

Free shipping not displaying in listing | Shipping | eBay Community