Releasing an app on Play Console has several release steps: internal testing > closed alpha > open beta > production
I'm in internal testing phase, but no one on my testers list has been given an invite. I created the list, including my email and another that I know is valid, both Gmail accounts, but no email invite. There is an option to "save" after managing testers, but there is no "send invite" button. All I missing something?
The system doesn't invite them, you have to give them the opt-in URL yourself. I think the email list is just for access control.
The Google Play Console Help details this step:
After clicking the opt-in link, your testers will get an explanation of what it means to be a tester and a link to opt in. Each tester needs to opt in using the link.