Missing out on a position due to false HR advice. What should I do?
This, and your earlier question, seem to be very localized. I think that you need to handle it locally. Go back to HR with your new evidence and seek new advice. Challenge it if necessary. Go to whomever is responsible for the new position with whatever advice you get from HR along with your new evidence and ask for advice there. If it is at all unfavorable, ask for an exception. 

It is possible that there is nothing more than a lack of communication or a misinterpretation of rules. But you won't get out of your trap without bringing it to everyone's attention. 

Perhaps you will just learn how the other cases are not the same as yours. But perhaps you can get the gears unstuck with a bit of jiggling.