1. In Library grid view, click on the collection in the Collections panel on the left, showing only pics in the collection.
2. Do Photo > Stacking > Collapse All Stacks.
3. Make sure the filmstrip is showing.
4. At the top of the filmstrip, you'll see "Collection: collection-name x of y photos". y is the total number of photos in the collection, and x is the number of photos showing in grid view, i.e. the number of photos that are top of stack or not in a stack.
That is true. However, the sub-Collection name in the left window still shows the total number of images, not the top images only. That is what I want so I can determine the number of photos that I will export to make a show with another application. Hence, I need the number next to the subcollection, an even better, the Collection, to have the number of photos on the top if the stacks plus the individual photos.
so I can determine the number of photos that I will export to make a show with another application.
I understand that it would be more convenient to have the number in the Collections panel. But doesn't the number at the top of the filmstrip get the job done?
Sure, if I want to open every collection in my Collection Set one at a time. It can be done, but it means a bunch of extra steps. My current project has 15 collections in the set. In fact, the best solution would be for the Collect Set header box showed just the total of top level images in the set.
You can submit feature requests in the official Adobe feedback forum: Photoshop Lightroom | Photoshop Family Customer Community. Product developers actively participate in that forum (but not here much).