Windows 10 PM+ V6 build 5438
There seems to be a change in behaviour with the new update.
In a contact sheet, if I select all, then right click on a random image and select "include in catalog", only the image that I right clicked on gets the green dot. (I haven't checked whether the others are actually included in the catalog or not.). But if I select "include in catalog" from the main menu, all selected images get the green dot.
If I select all, right click and select "copy", all images get copied as expected.