Sounds to me like your audio engine is dropping out while the transport isn't running.

You can turn it on by clicking on its icon in the lower left corner of the transport module.

To stop it turning off go to Preferences--->Audio--->Playback & Recording and check "Play effects tail after stopping"

That should sort it out for you.
 
If you are new to MIDI and want to know a little more about routing check out this video

I have this one project at the minute where I have 3 audio tracks and 1 synth so far (Rapture, which works). When I try to add additional synths, either by laying a simple instrument track or setting up separate audio and MIDI tracks, no sound comes out of them. The MIDI from my controller isn't registering on the MIDI tracks. Funnily enough, the MIDI is registering in the soft synths themselves, but no sound is coming out. It's really confusing. 

Then, if I start a fresh project and set the same synths up in exactly the same way, they all work. I really can't figure out what is different about this project that it will only allow one synth to work. 

Try increasing you MIDI playback buffers. In Prefs-->MIDI-->Playback & Recording-->Playback

The default is 250, upping them to 500 should help.

HTH
 
Thinking about it and re-reading the OP that'll probably fix the OP problem too.

Mine are already set to 500. I really wish I knew what was causing this - there is obviously some setting in this particular project which is stopping synths from playing back, or MIDI tracks from registering. 

I'm going to guess:

A. Initial volume widget in MIDI track header or CC7 controller in the clip set to 0, silencing the synth every time you start playback.

Or

B. Zero Continuous Controllers When Play Stops is enabled in Project > MIDI preferences, and you don't have the initial volume widget enabled or a CC7 event in the clip for searchback to reset it on start.

brundlefly


I'm going to guess:

A. Initial volume widget in MIDI track header or CC7 controller in the clip set to 0, silencing the synth every time you start playback.

Or

B. Zero Continuous Controllers When Play Stops is enabled in Project > MIDI preferences, and you don't have the initial volume widget enabled or a CC7 event in the clip for searchback to reset it on start.

This has definitely happened to me in the past.... made me crazy until I figured it out.

Hey, Jim.

I sent my private email to you in a private message.  Can you possible send me the GM midi track that you are having these troubles with?

I'd like to look at it and see if I can trouble shoot it at my end, then post back on what is going on with it.

Bob Bone

OK, Jim - thanks for sending me your trauma (midi file).

I figured out why nothing is being played, even though the meters are moving.

They have each track assigned to a different midi channel (all events on the 2nd track are recorded on midi channel 2, etc.).

The reason it works with TTS-1 or whatever it's called is that it is multi-timbral - meaning it can play more than one sound on up to 16 midi channels at the same time.

So, when everything is assigned to the TTS-1, each instrument is on a different midi channel by default, and it just works.

When you try to use different synths for the tracks, you have to make sure you set the synth up to match the midi channels in each track.

When I opened your project and assigned Kontakt 5 to play the 2nd midi track in your project, on a piano sound, I saw the midi track meter moving but no sound came out.  Once I looked at the midi events (they have some really weird cc 7 events galore on that track by the way), anyways once I looked at the events, I went back and set the Piano sound in Kontakt to play on midi channel 2, and I also set the Midi Output Channel for that midi track to channel 2.

Then, everything for that track played no problem.

It is going to be the same thing for each of those tracks.

Once you make your synth assignments for each track, make sure you have the midi channels set to what the track is expecting, and you will be fine.

Please verify this works with YOUR project, and I will be up for at least an hour, if you want to post more questions - and I also sent you my cell number if you would rather call me.

Hope this helps you out with your troubles here, 

Bob Bone

That would explain it, and that would fix it.  Nice detective work, Bob.

It's kind of fun- and I enjoy helping folks.

I am disabled, with a BUNCH of herniated discs, so I generally have some time available to do things like this.

I also have 2 bad knees - one got an injection of stem cells, and is happily growing new cartilage in the joint (VERY cutting edge).  The other knee is getting replaced in a few weeks.

The 9 herniated discs will be undergoing minimally-invasive surgery in the first part of the year.

But in the meantime, I work on my music and work some at trying to help folks with X2.

Bob Bone