I'm having an issue but haven't exactly been able to nail down for certain it's the beta itself. If I have my EarPods in and start a call, I can't hear anything. I have to tap the Speaker button and then and tap it again and then proceed with the call using the Apple EarPods. It works fine if I quickly switch back and forth but shouldn't need to.
I don't think the beta is the culprit, although I could be mistaken. I've yet to experience what you've described while using my Apple EarPods. Maybe those who have will reply soon...