It seems product bug.
Does any one faced this issue?
I've been struggling with this same issue on the same platform (5.5 sp2). Here is what I know so far:
When you are browsing the DAM tree under the Digital Assets tab and open a jpg, then the asset editor retrieves a list of image-specific fields from /apps/dam/content/asseteditors/image/jpeg/formitems .
When you use the DAM Search tab to find the jpg, then the asset editor retrieves the list of generic fields from /apps/dam/content/asseteditors/formitems .
This issue also affects PDFs. The Digital Assets tab will use the pdf-specifc fields from /apps/dam/content/asseteditors/application/pdf/formitems but the Search tab will use the generic fields from /apps/dam/content/asseteditors/formitems .
In other words, the DAM Search widget isn't loading the desired fields into the asset editor. You can force the asset editor to load the correct fields by refreshing your entire browser. I may try to patch this by overlaying the DAM Search widget if I can find it.
Adobe Daycare has said this dam search display issue is resolved with CQ 5.6.1 which will be released later this year. I didn't try to fix it with an overlay.