Kontakt frequently likes a little bit of the sample file past the orange sample end marker in the wave editor. If you’re experiencing clicks or odd artifacts at the end or release of a sample, it can usually be fixed by sliding the orange end sample marker to the left some. For tightly edited samples, you may need to look for a zero crossing somewhere near the end of the sample file to move the marker to. Messing with the sample speed, tuning and various envelopes etc. (all the time, in other words) can also introduce end of sample glitchery that is almost always fixed with this remedy.
The BooTweak Original Instruments have the sample markers in a good spot (for the most part, no 100% guarantees, lol), so this is mostly a tip when using 3rd party samples in a BooTweak instrument.