I am in the process of looking into this issue.
Just to explain
All up until BE 15 FP2 you could select (NDMP Option) files and folders for restore from the Resource View graphical tree, however if you selected a folder of volume and then deselected some files within the folder, then these deselections actually become excludes and are ignored by the restore option resulting in the restore job restoring eveything (even if deselected). The admin guide section covering NDMP (against multiple BE versions) contains a statement similar to "You cannot exclude files and directories when you restore to an NDMP server. Excluded directories and files are restored."
However this statement did not clearly explain that a deselection (or red cross) against an object in the restore selection tree is an Exclude. We had various customers feedback that this behaviour was NOT desirable. Hence in BE 15 FP3 changes were made to block deselecting based on the customer feedback. My current investigation relates to this potentially not working in a desirable way as it appears we have limited selections to folders and volumes.
I will update when I have more information
Note: There is a slightly fiddly workaround involving creating Include statements manually in the Details View to restore individual files. (don't select anything in Resource View "tree") do it all in the Details 'text" View