Same here. We tried to release a new app to internal testers yesterday and it just won't send out the emails. I've tried all the suggestions about removing/re-adding/re-sending/ using Safari and none of them have worked. I tried again this morning and it's still not working. Someone at Apple needs to fix this urgently. We're made to jump through all those hoops to get our apps out to testers, then let down by things like this.

Can you please fix this? It's a real pain for managing user lists. I don't understand how the App Store Connect site has so many bugs in it. For a company which makes us jump through all these hoops in the review process you'd think Apple would apply some quality control to their own software.