Given the page hierarchy A -> B -> C, when you move C under A and remove B, what actually happens is that first B and all its children are deleted (or marked as deleted) and then C is tried to be created with only the subset of information that is detected by Releasebuilder. This then results in a new, incomplete page.
first move the page and transport that move from staging to production, then do the delete and move that forward.
A fix is available here. This will make sure that the release builder will export the whole page information, if the content or derivation parent is changed.