I have solution on our end, the issue we were facing is identified on this post from another thread: Issue with submitting to OIN: Submission Tester fails and closes a window after the auth redirect - #4 by kyleva
When navigating to our app’s login page, the app automatically sends a request to our backend authentication service to check if the user already has a valid session. If the user is not logged in, it responds with a 403 error. This error is what was causing the test to fail event though the SP sign in step was showing a green check mark (the test doesn’t show the failure until Okta sign in for some reason). I had to update the SP initiate URL to point directly to our backend auth service and bypass the frontend login (avoiding the expected 403 error). Also, as @Tahir52 has discovered, sometimes the Okta browser plugin stops working correctly and it must be removed and reinstalled. After updating the SP initiate URL to avoid the 403 error AND reinstalling the Okta browser plugin I was finally able to get the test to pass.