They may not have been picked up by UpdateMedia yet.
Look at Web admin --> files & media --> media file sync. DO NOT, under ANY circumstances, attempt to synchronize "/home", "/home/{user_# or public}" or "/home/{user_# or public}/data" - if you do this, you will have all kinds of crap in your media list, like the setup movies and test sounds, and you will never be able to get them out. Only synchronize directories UNDER "/home/{user_# or public}/data/" - never "/home/{user_# or public}/data/" itself, or anything higher.
Navigate on the left to "/home/{user_#}/data/{whatever media you want}. Click the "Resynchronize" button in the right pane. Go get a coffee - it will take a minute. Wait until it's done - if you close the popup window before the update is done, it won't finish.
By the time you read this, UpdateMedia may have found them - so check first...