I'm having trouble with the dummy objects because when I place them in the CK they're there but when I go to where they should be in-game there's nothing there, does anyone know what the problem could be here?

Dubble click the dummy item go to the Leveled Item tab and choose an item from the drop box or type something in filter.

Well, I've choosen an item from the tab but it still doesn't appear.

bump

bump bump

Could someone please help me with this?

This is listed as a medium bug in the Unofficial CK Buglist: http://www.gamesas.com/topic/1347249-unofficial-creation-kit-bug-list-2/

Dummy Items Issue (thread): http://www.gamesas.com/topic/1346621-dummy-items-issue/

This could also relate to the item you placed in the dummy object. If it's levelled too high or too low for your character, it simply won't appear. For example, a level 1 character won't see a dummy weapon with an enchanted Elven sword attached.