By 'upside down' I didn't mean not deployed. You do get an E for effort there though.
The single lobe side should fit into the stock ferrule notch when closed...and conversely the two lobed side should fit flush with the bottom of the stock when closed.
You have a fifty/fifty chance of getting it right on the first try...
You need to take it off, and flip it 180 degrees from it's current position
inside the bayonet handle.... and then reattach...basically, the only other way it can go.
Get a cleaning rod in there and you will be set.