Whenever you test your game on a local server and purchasing a gamepass on that local server, UserOwnsGamepassAsync will always return false, even when you successfully purchase it on the local server.
What I expect to occur is that UserOwnsGamepassAsync would return true after I successfully purchase a gamepass in a local server.
Currently, I am using Roblox Studio Version 0.410.1.361262 on Windows 10 Version 1903, OS Build 18362.476.
The video below shows this bug in action: