I created animations in InDesign CC 2015.4, either fade in or fly in, for most pages of my fixed layout children's book. After I uploaded the exported ePub file to iBooks and then downloaded to a variety of Apple devices. Perfect on the MacBook Pro and Air, on the iPhone (9.3.3) after much tweaking, but not on iPad. Even when animations are set to hidden until animation begins, some appear, then disappear and come back. On the fly-ins, I thought I solved the problem by extending the path farther off the page. The problem is always with the first item to appear on the page. I went to the Apple store to test it on one of their iPads and have asked two other people to test. Different problems appear on the different iPads but both are buggy. I can send a promo code for anyone with an iPad to test, as well as the INDD doc. Adobe tech support is blaming the problem on Apple but that doesn't seem right. I saw an answer to another post about versions of InDesign. If the original file for the printed book was created a year ago but saved with each update as a new file, could this be causing problems? I definitely exported from CC2015.4 and CC isn't showing me any available updates.
The fix was to uncheck the hide until animated box (checking it had been a desperate attempt to get the animations to work but never should have been needed) and add a delay of .25 secs to the first animated item, which isn't noticeable.