I've seen this before... Had it happen on XPages.TV and in the XPages Media Library app I've put on OpenNTF. My solution was to just expand the repeat so as not to need the pager.
This has come up before.. I think there's something on StackOverFlow once.. not sure I've found the answer. Haven't really tried.
In my case the repeat was coming from a bean. And it seemed to get lost with the data or something when the pager is used. I do forget the details a bit but I'm sure I'll be running into this again.