OktaAuth.isLoginRedirect always evaluating to false

I’ve tried checking the OktaAuth.isLoginRedirect() result in multiple places (mainly the signin redirect page), but it is always returning false even though I’m able to sign in. I’m using a SPA app with React. I’ve checked the sample React code and it doesn’t make use of this method. I want to properly check the id/access tokens and if invalid force a login, otherwise proceed to the home page of the app.

Has anyone else had this or similar issues and how did you resolve?