In a layout document, all objects are floating unless they are contained within the text of a textbox or a shape. I don't imagine that, or the wrap settings mean much here.
An object (or a grouped object) can only be on one page, but if you drag an object so that it spans the border between two pages. Pages displays the part that is on one page normally and it displays the part that overlaps the other page as a "ghost" image similar to what you are showing. I haven't played with it enough to figure out how Pages determines to which page the object is "attached."
My guess, which is only a guess because I can't duplicate it, is that you are seeing a variation of a bug that some people have run into with long word processing documents where the user interface gets confused with respect to the page boundaries and can't select text toward the bottom of the page near the end of the document. Some part of the graphic processor thinks the bottom of the page is a few centimeters higher than it really is, so it is showing the object as if it is attached to the next page. My suspicion (again, just speculation) is that it is some kind of rounding error in the conversion between points in the document and pixels on the screen when the zoom is set to something other than 100%, which seems consistent with the problem getting progressively worse the further you go down a long document.
If this is the case, some people have had (at least temporary) success with copying the entire contents and pasting into a new, clean document, but since I have never personally encountered the anomally, I don't have direct experience of that.
