When you create a track 1 (e.g. using TTS-1), put some MIDI notes in there and then add a Bus "D" (which outputs then to Master).
Then set the outout of that track 1 to Bus "D".
Then SOLO the Bus "D"
Play back; You hear the output of TTS-1
Then freeze track 1.
=> the created waveform is pure silence, although its routed to Bus "D" which is SOLO and although playback works for it...
See in this example project:
FreezingTest.zip