Larry, before I erase my thumbnails, I just want to check that this is going to work. When you look at the tag info for audible files, is there anything in the "Image" field? For me there is nothing, so I'm wondering if I might have deleted the art somehow.
There are a few parts to the answer. First, I'm not sure you CAN delete art from Audible files. I know that unlike mp3 files, MC does NOT re-write Audible files when changing tags, so it would seem to follow that MC wouldn't be able to erase art from Audible files. This means that if the file has art in it, you "should" see it after you erase/rebuild the thumbnails.
That said, it appears that there is another issue here. I have some Audible files that continue to say "Inside file" for the art even though no art actually shows up. I don't know if this is a bug in MC, or a bug with the actual file.
On top of this, I've also found that some of the files that I've downloaded recently (BEFORE build 114) don't "currently" show art even after the thumbnail "rebuild." I tried downloading some of these files again from Audible, however, and these new downloads DO show art. In other words, the file I downloaded with a version of MC12 prior to build 114 does not show the art, but when I download the SAME file with build 114, I DO see the art. I can't say if the file has been changed in the interim, but I don't know how likely this is. It's possible that MC12 still has some sort of bug with displaying art in Audible files, and that if this bug was fixed, I would not have to re-download the files from Audible in order to see the art. At this point, however, I obvioulsy can't say for sure what's happening under the hood.
To address your question directly, I've seen different things for different files. Some of my Audible files said "no image(s)," some said "inside file." Now that I've installed 114 and rebuilt the thumbnails, I STILL see some saying "no image(s)" and some saying "inside file," but I ALSO see art for many of the files.
My advice would be to go ahead and erase and rebuild the thumbnails since there is no downside to this (other than it taking a little while to finish.) This process does NOT effect the actual files -- it simply rebuilds MC's thumbnail database.
I wish there were an option to "rebuild thumbnails for selected files"
I've requested this before as well. It's frustrating to have to erase and rebuild the ENTIRE thumbnail database just to get ONE file to show the art, but this is exactly what you have to do in certain situations.
Larry