Hi !
What the sample contains is irrelevant. The OT doesn’t know or care about how much silence you have or don’t have at the beginning of a sample. Therefore, it has to do with how you’re trimming your samples before importing them, or how you’re stretching them in the OT.
Double check and make sure you’re trying this with exact length samples and at the right tempo. If that works, then continue troubleshooting by trying stretching.
One example that quickly comes to mind is the fact that the Rate parameter, if set to Pitch in the playback menu page, will slow down the playback speed of a sample. In the case of a loop, it would slow it down, effectively making it come later, and also truncating itself as it is retriggering.
Hope this helps, keep us posted.
Cheers !