Views block order breaks slideshow cycle

On a D7 site we are using one View to create two slideshows that cycle through content in a block. The two slideshows come from using separate displays, each one filtered to the specific CT being displayed. Each display creates a block. Both blocks are put into the same sidebar 2 region (the theme is based on Omega), one above the other in the sidebar. So far so good. Both slideshows cycle, and life is good.

As soon as we place one block BEFORE the other (so it is now ABOVE it on the page), the later display fails to cycle.

So far we've tried -
making the order of the displays match the order that the resulting blocks are displayed (I know, sounds stupid by we're desperate)
turning off the effect of the first display
playing with the timing and delay of the two cycles

None of those fix this.

If we put them in separate regions they work again. If we put them in the original order they work again.

Does this trigger any thoughts with anyone on what might be going on?