There's not nearly enough information there to answer your question. What's your setup? What's the WG config? How is set up to operate? What IP are you checking?
Let me guess, you "restart" the WG interface by reloading the network service with LuCI.
Instead, you need to put the WG interface down and up again, i.e. completely stop and start it to properly apply the changes.
Or restart the network service instead of reloading using the system startup page.