We use Skype for Business, and it's a common cause of issues. We have constant issues with different individuals not being able to join meeting invites (although the dial in always works, the app doesn't), people being able to join but video/screenshare or audio not working, it refusing to acknowledge the leader so it doesn't start, etc.

Our IT team has sent out a bunch of surveys trying to triage the cause of the intermittent issues, but haven't been able to result the problems yet. It drives us nuts though. And that's with the resources of a Fortune 100 trying to deal with it.

Glad it's working well for you, though. That gives me hope they can't get it working more smoothly for us eventually.