No code here, just an observation from a month of developing for iOS. There can be a delay on any action taken in the App Store Connect console. Upload a build, add compliance, add testers: sometimes the result of your choices aren't reflected in the App Store Connect console for minutes, up to hours.
Patience. Instead of rebuilding or rage-clicking, just wait a reasonable amount of time for the processes to complete.
To assist, Apple often sends an email when some actions are completed, like releasing a build: "Your App - Version 4.7.5 (216) for iOS is now available to test". If you're expecting an email and it hasn't arrived, you're likely in some queue that will resolve itself.