My supposition is that those PDFs that only display an icon of the first page were imported with different preference settings, as externally linked files, and that the paths to the external files are now broken.
Examine the Path field in the Info panel for such a document. The Path refers to the location at which DT Pro expects to find the original PDF file.
If you can’t figure out a remedy from that information, send us a Support email and we’ll try to help clear things up.
Bill, you were right on the money. When I checked the path as you suggest, it pointed to a folder on my desktop and there were no longer any documents in it. I had assumed that I already had everything in the DB.
I was fortunate in that those docs were on my wife’s computer and I just copied them to the place where they should have been on my desktop before and I see the doc, not the thumb. Now that I think about it, I have have had “thumbnails” checked in the Prefs.
So in one sense, my problem is indeed solved, I can read the documents.
I do have a question, however, All those files are in four separate folders within a holding folder on my desktop, and that’s what the path points to. What I’d like to do, however, is have all those files (actually, it’s only about 34 MB) within my DB in DTPro so that I can get rid of them on the desk top. Can I simply re-import them into my DB with the current Pref settings?
Thanks so much. Man, where would we users be without you guys online???
Yes, you can reimport the PDFs into DT Pro with Preferences set to copy PDFs into your database Files folder. Make sure to use File > Import > Files Folders import mode. (Using File > Index will (I think) still leave the PDFs externally linked.
Here’s a complicating factor: You will end up with duplicates of the PDFs. So you will probably want to delete the current PDFs before importing them again, with your new preferences setting. Here’s an approach that should work:
 The Paths of all the ‘old’ PDFs that you wish to delete and reimport contain the name of the holding folder. Right? If so, go to the next step.
 Copy to the clipboard the portion of the Path that contains just the name of that holding folder (without slashes).
 Select Tools > Search. Paste the holding folder name into the query field. Now press the Options button and choose Search for URL/PATH instead of All. Make certain the options are set for a database wide search, with no restrictions such as Phrase or Label or State settings that might miss or add to results. This will restrict the search to those two fields (Path and URL) in your document’s Info panel.
 Click on the Loupe symbol or press Return to initiate the search. You should see a results list that consists only of the previously entered PDF files.
 Here’s a quality assurance step. Let’s make certain that all the documents in the search list are PDF files. Here’s how: With your search results window open, select View > Sort > by Kind. Select the first document in the list. It should show a PDF page icon. Now scroll to the bottom of the list and select the last document. If it also displays a PDF page icon, the entire list contains no other file type. I threw in this QA step just in case your holding folder’s name might show up in some other tile type such as in the URL of a Web page. If so, find a range of selections in your search list that only contains your PDF documents.
 Now select all of the PDF search results and delete them. If a dialog appears asking whether you also want to delete them from disk, tell it that you don’t want to do that. Otherwise, it would delete the files within your holding folder, and you would have to import them again from your wife’s computer.
OK. Now you are ready to reimport the contents of your holding folder using your new preferences setting, and using File > Import > Files & Folders. Your options would be to select either the holding folder, or to select the four folders inside it – that’s up to you as regards your organizational structure.
Now, go to the DT Pro’s Scripts menu. Select Scripts > Export > Backup Archive. This will run Verify & Repair, Backup & Optimize and save a compressed, dated archive of your database to a location of your choice. An external drive might be a good idea.