I'm running CC 18.104.22.168 on Mac OS X 10.9.5 and found an issue downloading items from the Creative cloud market.
Searching for a vector icon (such as "car") finds a lot of car icons. However most seem to simply be called "car"; which means the first item (named car) you click download will download to CC Folder > Market Downloads > car.svg. Any future "Car" options will not download until you delete/move/rename the car.svg file to allow the new one to take it's place.
None of this seems to given any alert or message that even trying to save the file, so you can spend a while thinking a specific file won't download, because that one has the same name as a previous file where as others around (with different names!) work fine.
Renaming has solved my problem, but probably something that needs fixing!