Redirect_uri "invalid" error despite correct callback domain configuration

  Issue:
  I'm getting this error when trying to authorize:

  {"message":"Bad Request","errors":[{"resource":"Application","field":"redirect_uri","code":"invalid"}]}

  My setup:
  - Client ID: 199758
  - Authorization Callback Domain (in Strava settings): runcoach-backend-a8d975.azurewebsites.net
  - Redirect URI being sent: https://runcoach-backend-a8d975.azurewebsites.net/api/auth/strava/callback

  Full OAuth URL:strava.com/oauth/authorize?client_id=199758&redirect_uri=https://runcoach-backend-a8d975.azurewebsites.net/api/auth/strava/callback&response_type=code&scope=read,activity:read_all,profile:read_all
 

  What I've verified:
  - Callback domain has no https:// prefix
  - Callback domain has no trailing slash
  - Domain exactly matches the redirect_uri domain
  - Client ID matches my app