TTT is design to follow a call in it's entirety (call setup to call release) across the network. (To any carrier belonging to current MNC)
The old plug-in does not do this, which is why this fork of the plug-in and TTT exists.
The TETRA Demodulator plug-in and TTT will only follow on going calls only if there are call setups still been sent.
Private calls only send a call setup once, so if you don't act on it the first time, it will never switch to it later.
Just because the 'calls list' shows calls, it does not mean that the call is still on going. (no call setups).
The control channel does not indicate when a call is released, that's why a timer is used to clear call(s) from list.
An exception would be if a call was on main carrier, then it should clear off the list as soon as the release is seen.
This means that if a call that lasted for only 5 seconds, it would still be visible in the list for 30 seconds. (if not on main carrier)
TTT does not switch to calls that are shown in list because there is no way to know for sure if the call is still in progress (if no call setups are been sent), most of the time the calls have completed and you just end up sitting around waiting for timers to expire before it returns and waits for next call to occur.
If you see "Call timeout occurred - did not see D-Release" it's because the 'Call Timeout' value is too low.
The BS usually allows X time (no talking) between 'overs' before it releases a call. The 'Call Timeout' value should not be less than this X time.
45 seconds is a good around value and it works better when private calls are seen, these seem to allow for larger pauses between 'overs' than group calls do.
TTT dual works best if your network uses multiple carriers. This allows priorities and private duplex calls to work correctly.
If your network (MNC) only uses the main carrier and you don't need or see private duplex calls, then TTT single mode would be OK to use.
Missing calls on a trunk network is a fact of life, you can never hear all of them at once so worrying about it pointless. The best you can do is use the priorities to follow the groups you are more interested in.
Latest version (v1.7.1.0) can be found here: Release post