That’s strange. First, I thought it was that Width was less than 100 (you stated it isn’t). Then, I was guessing it was the Channel One (left) cabling, but you’ve said it behaves correctly with higher rates.
I haven’t noticed this issue, or had a chance to test it out yet, but I have a quick question: By “slowest rate”, are you setting this at 1.00 Hz. [Tempo Off], or 1/4 [Tempo On]?