Hi, pretty cool plugin - but for simply pitching the tail I find that I have to use a kick with a VERY long tail for it not to get too short after pitching.

Previously I used the built in transposer in Logic Pro which barely changes the length of the kick sample, even when pitched up 12 semitones.

Am I missing something?

It depends - if you're using the "Resample" algorithm you'll end up with the most basic pitching possible, I wouldn't recommend using that unless you have a good reason for it. You should probably stick with Time Machine.

If you're already using the time machine algorithm and you're noticing this problem, that's normal as well depending on the sample you put in. Due to the nature of the algorithm, you're better off using samples that are slightly longer than your beat length. For example, if your track is 150 BPM, don't make your kick sample exactly 400ms, make them slightly longer such as ~450ms, because otherwise the algorithm won't know how to fill up the empty space at the end.

Alternatively, you could just set the Stretch knob to ~111% to compensate for the artefact.