Yes Neil, I did try that and uncovered yet other problems with DS 8.51.

As a programmer, I knew that if enabling "Only show screen sized or bigger wallpapers" worked, in that it made DS 8.51 find ALL IMAGES regardless of size, that would indicate even more severe problems with 8.51.  As it turned out, it did reveal yet another unexpected problem with 8.51; when enabled, DS 8.51 does not show ANY images in some directories that contain ONLY images that are larger than the screen size.

So, no, enabling "Only show screen sized or bigger wallpapers" does not work, it just creates additional problems; at least on a Win 7 64-bit Pro system.

Again, DS 3.50 displays all images, regardless of image size or number of images in a directory (folder.)

Perhaps DS 8.x is not truly compatible with Win 7 64-bit Pro.

There is a simple test that your team COULD do to verify the existence of this problem:

1. Locate a system running Win 7 64-bit Pro, with additional average software also installed;
   
   
2. Have DS 8.51 running;
   
   
3. Create several "wallpaper" image directories (folders), each containing a 100 or so *.jpg images of various sizes (smaller than screen-size & larger than screen-size);
   
   
4. Count the number of images displayed in the DS 8.51 interface by individual directory (folder, just for simplicity)
   
   (On my system, DS 8.51 displays the images in rows of 4, so just clicking on the top right image, and using the down arrow, you can easily count the rows one at a time and multiply by 4);
   
   
5. Compare the count to the actual number of total images in each of those directories (folders.)
   
   
   Here is a short sample of a few directories on my system, and the number of *.jpg images found by DeskScapes 8.51:
   
   Directory A contains 13 JPG images - DeskScapes 8.51 shows 10
   Directory B contains 832 JPG images - DeskScapes 8.51 shows 0 ("No matching backgrounds have been found")
   Directory C contains 100 JPG images - DeskScapes 8.51 shows 61
   Directory D contains 739 JPG images - DeskScapes 8.51 shows 189
   Directory E contains 109 JPG images - DeskScapes 8.51 shows 44
        Directories D & E contain a combined 848 JPG images - DeskScapes 8.51 shows 233
   Directory F contains 1289 JPG images - DeskScapes 8.51 shows 1265
   Directory G contains 18 JPG images - DeskScapes 8.51 shows 9
   Directory H contains 344 JPG images - DeskScapes 8.51 shows 3
   Directory I contains 3765 JPG images - DeskScapes 8.51 shows 0 ("No matching backgrounds have been found")
   
   DeskScapes 3.50 seems to find ALL OF THEM (to be honest, I didn't actually count the directory where there are 3700+ images, but thousands are accessible by 3.50, which is more than 0.)
   
   

IF they do see the problem, (as well as the blackout issue, mentioned in "[Win8.1] "Show desktop" button black screen" (https://forums.stardock.com/480581/page/1/#3666561)), uninstalling DS 8.51 and installing DS 3.50, they will likely see that all problems disappear.  Counting the images in DS 3.50 is a little more cumbersome, but relatively easy (they just need to count by 1 instead of 4 at a time.).

If that does fix the issues, the programming team needs to compare the code for image retrieval in both (3.50 & 8.51) versions.  Unless 8.x is incompatible with Win 7, they should just be able to modify the 8.51 code with the older 3.50 code.  The "black screen" issue would of course be elsewhere in the code (that problem did not happen in DS 8.1.)

Since this is an issue that I have tried to have StarDock resolve for over 3 years, it really is time for someone to perform the above simple test; just doing the 5-steps above, will take less than 45 minutes.