Originally Posted By: macnerd10
I would remove the extra numbers in the filenames (they are all different from the format of the files that show pictures) and see if this works. I have seen before files that would not even open in the intended application because of some "forbidden" syntax in the filename.

Well... it is almost certainly no coincide that the very files which lack a preview in Finder also all contain the [same] string “-5MB-file” in their name.

I don't know what the exact reason is (and confess my interest is now waning), but tend to think that it indicates some sort of special option(s) for saving a reduced-size file... which might intentionally omit the preview info that Finder (or whatever) needs.

[probably a little RTFM about the particular app in question would help]