That’s weird. I just tested it with a friend (I’m on Endeavour, she’s on Win11, the server is VPS with Debian running the newest Synapse and Element-web). Audio works fine both ways with no mic config required, streaming is a little laggy when viewing the screen and stream next to each other, but that’s all.
EDIT: No, you’re right. Audio within streams seem to fail. I remember Discord having the same problem (hence why I use Vesktop), but if Windows also suffers this shortcoming? I’m pretty sure I remember it working a month ago, so there should be a bug report in Synapse (or element).
It’s still in beta and audio appears to not always work when streaming. Though, there’s recent activity on the related issues, so hopefully it gets out of beta before Discord alienates the regular user.
I tested it a few days ago and besides the audio problem it appears to work very well.