I had a similar problem after buying a Husqvarna saw online (meaning it came unassembled -- not from a dealer). Discovered the problem was a round plastic white spacer that was preventing the case from closing tight and also preventing the chain brake mechanism from working correctly.
No idea if this is what's wrong with your saw though doesn't hurt to check. Make sure there are no plastic spacers inside your clutch case (where the bar holding prongs are)! These are meant to prevent jiggle during shipping and should be removed!
Thank you. Looked up and called a dealer. He said the Weed Eater One accessories were shipped last week and he'd have the bagger in his store soon.