Default Sine and also some vsts - produce micro click on transport start or stop. Especially one can hear it if play Unify without transport started - just as an standalone instrument. I think, 2-3ms fadein-out could help...
Per the title of your post, I don't consider this a "bug", but I will put it on the to-do list for future consideration as a "feature request".
I'm unable to reproduce any click when playing notes with the default sine patch. The Sine Wave Synth (which is only intended as a test sound-source) always begins each new note at the start of the sine waveform, where its value is zero, so there should be no click. There might be very slight clicks on note-off, because Sine Wave Synth uses a simplistic fade-out technique instead of a true envelope, but you would only hear it on the very loudest, lowest notes, and it has nothing to do with the transport.
Some third-party plug-ins do cut off notes abruptly when the host transport stops. This is a convenience in a DAW, but not so much in a live host like Unify. Some, but not all plug-ins that do this, also provide a user preference setting to disable it. Xfer Records Serum, for example, has a checkbox in its "Global settings area called "Silence note + effect tails when host transport stops".
For plug-ins that don't don't provide such control, the only solution is to use a different Trigger mode in Unify's Transport, e.g. "Manual start/stop". That's why we provide multiple trigger modes. If you need this for just one plug-in among several, and you want to keep the default "MIDI / Quick Stop" mode for the others, put the problem plug-in into an embedded Unify instance, and set the embedded Unify's Transport to "Manual start/stop". You may also need to experiment with the "follow host" options as well.
Thanks for an answer. That`s what i actually do just use another trigger mode.
I found that this click depends on buffer size (in a case with default sine)... on 256 it dissapears almost.. on 512 i can here it... Not a huge issue actually... but i always come in touch with it.
Thank you Shane! Hope you`re well!