Can you pls take a look at our demo site and see if this is an issue there as well? I see that in the demo site too the image thumbnails don’t always sync with the text beneath. The reason is – when the thumbnail/iPhone slider was setup, the other slider was yet to be initialized. The syncing from the text to the thumbnail works fine – since that slider was initialized after the first one got initialized and has the required inputs to sync with the slider above. This is a limitation of flexslider implementation.