here's a video of said behaviour:
https://i.imgur.com/jV70WOa.mp4 (apologies for the low volume, but it should be audible)
you can easily reproduce this the following way:
1) load a sample of an 808 kick or something similar
2) set the envelope range to something large, like 96 semitones
3) set up a pitch envelope, from +96 to +-0
4) start playback from different positions, like i do in the video. the output will sound differently, depending on where you started playback from.
i can provide a project including the sample, if necessary
additional info:
this behaviour persists when rendering (where playback position would be start of time selection)
the "correct behaviour" (same behaviour as when rendering from sample start) seems to occur at distances of a multiple of 1/4 bar. these cancel out perfectly when rendering + polarity reversing on one