I have an app in iTunes connect that I'm beta testing with external users. Some invited testers are not seeing any app available for download in iTunes connect. What could be causing this? Thanks.
I have seen this where iTunesConnect shows the user has not accepted the invite to join (I don't know whether the user did not, or that ITC has the user in the wrong state). It seems that they still get the messages about new builds, but can't install them. I found that I could not re-invite them, even removing and adding their email did not help. The only way I found to fix it was to add a new alternative email address for those users.
Update I have now seen myself why gmail addresses are a particular problem. Opening an invite email in the gmail app and clicking the link does not work. Even if TestFlight is installed it only shows the app briefly and then redirects to the app store. If you open the email in the Mail app instead then when you click the invite link it opens in TestFlight and asks you to install the app as expected.