This occurs with any ams patch containing the following signal chane:
ENV module (any output) --> Lin. VCA (any Gain input) --> PCM Out.
(example patch attached)
Then, if ams' output port is connected to any Jack port, all Jack audio directing to this port is silent.
This 'muting'-behavior is inherited to ports down the Jack connection graph.
Disconnecting the chane again anywhere within ams or Jack brings the sound back.
Sending any MIDI note event to ams cures the behavior for the time ams is running (only with an MCV gate connected to the ENV),
to repoduce, e.g.
* start mplayer
* start ams
load relevant patch, e.g. bass.ams from example patches
* connect outputs of ams to the system playback ports mplayer uses
* disconnect ams or send MIDI note to ams
- sound is back