I think this happened when I changed the page numbering settings on my book from "Continue on next odd page" to "Continue from previous document." The problem can be summed up in one screenshot:
I assume the left-hand master page is being assigned to the recto and vice-versa, but I can't figure out what causes it or how to fix it. If I manually reapply the master spread, it's temporarily fixed but breaks again if the page count changes in a previous chapter. As far as I can tell, every page and master is set to the same trim size, and no pages have been moved on the pasteboard (at least, I don't think so). Help, please?
InDesign CS6, OS X 10.8.3.
From what I can tell from your screenshot, you selected the Page tool, as Peter suggested. You clicked on the left page of that spread to select it (the big handles around the selected page are indicating that). You checked Show Master Page Overlay which causes the display of the thick blue line, then you dragged the overlay so it was no longer centered over the left page. I recreated this below:
I think if you drag the Master Page overlay so it aligns on the page, you should be OK from what I can see. Then turn off the overlay and choose another tool.
Thanks, guys. The problem is persisting. Let me see if I can narrow it down with some more information:
Please let me know what else I can do to help you figure out this vexing problem. I really appreciate your help.
I think you (or someone else who might have handled the file) inadvertantly selected the Page tool. I'm confident that that's the only way you could get the display you posted. And it's the only way I know you could get the message about a custom page size. Here's a posting on how to check for custom page sizes set with the Page tool.
Sorry for the wrong link. I think they're reworking their website. Try this: