Hmmmm...could display size be an issue?
The debug message traces don't show any error messages (other than "routine" messages that do no harm), but I did spot one odd thing common to all the traces:
FlowArray.open.Calculate: calcing; dt_w=548, dt_h=0
That line shows the width and height of area available to the slide show, and a height of zero is definitely not right. The width seems a bit low, and one of them gave a width of only 248 pixels.
If the screen's too small, that might explain why the "slack" comes out negative a few lines later:
FlowArray.open.Calculate: Hslack? number: "-130.33333333333334"
That line says that there's a deficit of 130 pixels.
So, guys, what kind of displays do you have?