Workshop items no longer downloading.

I noticed that items I've downloaded from the Steam workshop recently (wrestlers, moves, edit parts) aren't downloading and appearing in game.  I'm subscribed to about 1900 items in total, but anything after about the 1800th item isn't downloading.  Is it possible I'm subscribed to too many items?  I have plenty of disk space and no mods.  I've tried restarting and clearing the download cache in Steam, but nothing appears to be working.  Any idea what's going on here?