[InspiredLife]

The solution I use for this (on a Nook Simple Touch) is to open the book in Sigil. Open the content.opf file in there. Hit CMD-S (Save). If the cover metatag was already in there, but around the wrong way, Sigil fixes it. If there is no cover metatag in there, and a cover image is selected, then Sigil will add the correctly formated cover reference.
In the odd situation where no cover image is embedded in the epub, I have to add it to the epub in Sigil, tell Sigil it is the cover image, then save. But all my epubs have embeded covers, just that the content.opf either has the tag around the wrong way or it is missing entirely.

It's a relatively quick fix, until B&N sort this out.

When I say "around the wrong way", I am referring to the tag being:
<meta content="cover-image-name" name="cover" />

instead of

<meta name="cover" content="cover-image-name" />

Not "wrong" by epub/XML standards, but wrong from the faulty Nook software.

I tried to hack together some python script with the help from folks on Stackoverflow... to scan through a folder (and subfolders, recursively, find epub files, unpack the epub, fix the meta tag in content.opf, repack the epub. I thought it would be a simple enough thing to do... but it was to no avail, as my python skills are zero, and no one was able to help put together such a script.

UPDATE: Looks like I don't even need to open the content.opf file. So long as the epub already has a cover image embedded in it, just opening in Sigil, hitting Save, and closing seems to do the trick.