I don’t know if this is an issue with Renoise or Roli Studio, but I’ll put it out here because they’re not as responsive.
For both Roli Studio Player and Studio Drums, any sample triggered on line 1 of a pattern is cut short, ending after a line or two rather than the full duration of the note/sample. All other notes sound fully, but (almost) every time the pattern loops back around to the beginning, the note is cut short again.