I have the same issue with my android tablet and Amazon fire tablet. On Samsung nothing happens after pressing update and then download and then nothing happens. Just spent £17 on a world for my son who now can't play it. On Amazon tablet it starts to update but then it gets stuck and the whole screen starts flashing. I really hope this will be fixed soon.
So my old marketplace items finally updated and I foolishly went to buy the kids new ones thinking this has been fixed, well surprise surprise, the new ones don't work! Stuck on update. Is this just the new reality now then? Because I won't spend any more money on marketplace. I've no idea how to get my money back either. I can't believe they're not fixing this or at least updating us that they're working on this, we have paid for these items that we now can't use.