don't know if this would technically be considered a "bug" but - let's say you put 4 jpegs on the same slot, so they play in sequence... then you set this to bpm mode at 4 beats. When they play through, one would think that each photo would play to each beat at the same rate - in fact the last photo always plays for a much shorter amount of time. it starts on beat, but ends too quickly compared to the rest, and loops back to the beginning too soon.
This problem occurs with all photo sequences no matter what the play mode is, but the 4 beat bpm is a good way to demonstrate it.