I appreciate you submitting a bug to Microsoft on this issue. I hope you will post anything you find back to this forum as I too am suffering from this problem.
I have been having this problem for well over a year and it is beyond annoying. I am very diligent in how I put my database diagrams together, and I refer to them regularly throughout the software development process.
I've attached a BEFORE and AFTER jpg so that it is completely clear to anyone what is happening. In the BEFORE screen shot, you can see the entities all carefully placed within the page breaks. In the AFTER screen shot, all I have done is choose to PRINT the diagram. You can see the print dialog box open in this screen shot, and you can also see how ALL of the entities have mysteriously shifted down by about 1/2 a page.
I've tried to "outsmart" the shift, thinking OK, if it wants to shift 1/2 a page, I'll choose PRINT a 2nd time to see if it will shift again. Problem now is that it doesn't shift anymore. It stays "perfectly" misaligned.