Photo/Video Media Libraries Don't Create Folders For Single Items

[HouseOfCards 95]

Libraries of photos or videos don't group into folders if the folder contains only one item...

As you see, each folder on disk is the name of the vacation, but the one folder (showing here as "Fish Feet") only has one video in it.  That "Fish Feet" video is in a folder on disk called "Cozumel, Mexico (2016)", but it doesn't get a folder in Emby.

[Happy2Play 9780]

Yes this is by design. 

As there are legacy system CollapseSingleItemFolders and per library CollapseVideoFolders hidden options.  The system option set to true globally ignores per library option.