I encounter a few timing problems that I try to narrow down. What you see here is a set of 6 MSOs that fade away after each other. (This is a trick to maintain beautiful sharp vector type in a title animation that would look pixelated if the type was part of the MSO).
anyway, when I swipe to the article, everything looks fine.
If I navigate to the article from the browse mode, the delay setting is ignored, every slideshow is appearing right away.
Settings of each MSO:
I used v21 with preview on device. Same result when going through the cloud (altough I got blank grey pages on the first try, then updated and saw my layouts).
Same behaviour occurs when you start swiping the article, then all the remaining MSOs appear at altogether.
Additionally, you see some color differences in the rasterized MSO compared to the background, although they have the same color used in InDesign (PDF folio).
It's 100% reproducable.
As you say, looks like the delay value is ignored when you get to the article by scrolling through the document quick browse.
You can regain some of the effect if instead of using 6 separate MSOs, you'll use a single 6 state MSO, but then you'll loose the ability to set individual timing.