redirect_uri always redirects to graph.api.smartthings.com/{path}

Having a problem with oAuth redirect_uri. No matter what I pass, it always redirects to https://graph.api.smartthings.com/{path}

For example, this:
graph.api.smartthings.com/oauth/authorize?client_id=&response_type=code&state=&redirect_uri=http%3A%2F%2Flocalhost%3A8080%2Fapi%2Fauth%2F53d31773e7c39774d36fa8ab%2Fcallback%2Fcustom&scope=app

redirects to:
graph.api.smartthings.com/api/auth/53d31773e7c39774d36fa8ab/callback/custom?code={code}&state=

instead of:
localhost:8080/api/auth/53d31773e7c39774d36fa8ab/callback/custom?code={code}&state={state}

I have a lot of other working oAuth integrations, and this is a new quirk. What could this be?

Thanks!!!

Bump.

Same here. Was able to get it to redirect to my internal IP, but using localhost never works.
Not ideal at all, as my internal IP changes routinely while developing…