I have one set of parent items where there is a thumbnail image showing up in the BOM section of the traveler.
 
There are two parts to the mystery:
1. The BOM component does have an image link, but it's set for Parent only.
2. The thumbnail that is printing is NOT the image for the component, it's the PARENT on the WO...
 
I have double and triple checked the above information. The only way I get get the traveler to print correctly is to set WO-C to Print Linked Documents as P. We have hundreds of items set up the same way, and it is only six items (all with the same Image Link) that we are having trouble with.  
 
The Thumbnail does correctly print in the header section of the traveler for the parent item.
 
Also, the Thumbnail of the component correctly prints in the header section of the traveler when we make a WO for it.
 
???