Hello,
We are in the middle of finalizing Airtime 2.1.3, and are offering a tarball version for anyone who is experiencing problems with 2.1.2 and occasional stream going silent when audio is still scheduled.
This problem only happens when Stream Settings are being changed at the same time as scheduled content is current being broadcast. If this is something that affects you, then please find the beta tarball available here:
A Debian package and a final tarball will be available this week.