Your system information

• Steam client version (build number or date): 1573176642
• Distribution (e.g. Ubuntu): Linux Mint 19.2
• Opted into Steam client beta?: [Yes/No] Yes
• Have you checked for system updates?: [Yes/No] Yes

Please describe your issue in as much detail as possible:

Steam Broadcast does now work on Linux in beta and it works so far, but it never records audio. I've already set to record audio from all sources. When looking in pavucontrol there is no record sink, so it doesn't even start to record anything.

Here's the log:

[2019-11-11 18:52:59] Begin session : ok (SessionID 1973869749351135007)
[2019-11-11 18:52:59] Upload thumbnail job: started (RelayID 1973869749351135007)
[2019-11-11 18:53:07] Upload thumbnail job: uploading 416x234 screenshot (22270 bytes)
[2019-11-11 18:53:21] Upload video job: started (RelayID 4491937615097458525)
[2019-11-11 18:53:22] Chat job : start listing to "{removed}"
[2019-11-11 18:53:24] Upload job : connected to "162.254.197.46:27050"
[2019-11-11 18:53:24] Upload job : init video 1920x1080, audio 0Hz
[2019-11-11 18:55:09] Upload thumbnail job: uploading 416x234 screenshot (15593 bytes)
[2019-11-11 18:57:10] Upload thumbnail job: uploading 416x234 screenshot (16987 bytes)
[2019-11-11 18:57:11] End session : SessionID 1973869749351135007
[2019-11-11 18:57:11] Upload video job: stopped after 227 seconds (OK)
[2019-11-11 18:57:11] Total video uploaded : 2340 kbit/s, 30 FPS, 2 seconds keyframe interval
[2019-11-11 18:57:12] Chat job : stopped (0 failed requests) 
[2019-11-11 18:57:12] Upload thumbnail job: stopped (RelayID 1973869749351135007)
[2019-11-11 19:44:22] End session : SessionID 5504695179164493257

Notice the 0Hz audio bitrate.

Steps for reproducing this issue:

1. Enable broadcasting
2. start a game
3. let someone join the stream