I have been studying and collecting the 1922 Series Springfields for 30 years. I have never seen, read of nor heard of a one round magazine.
I suspect the magazine spring has somehow gotten messed up. The floorplate of the magazines were not meant to be removed.
I suspect it could be repaired if the spring is the problem. M2 magazines show up on gunbroker, ebay and at gun shows.
If you find one make sure it is he original with the three little teeth on each side of the floorplate. Prices are in the $100.00
to $150.00 range. Make sure it has the small M2 stamped on the top left side, as does the one in your picture. Aftermarket
magazines show up for sale often in the $50.00 price range but they don't have a good reputation for functioning.
The 1922M1 rifles that have been upgraded with the M2 bolt usually, but not always, have the B suffix added to the serial
number. If your rifle has the bolt serial number engraved on the bottom with some digits on either side of the line where
the front and rear parts meet, it was probably done at Springfield Armory or one of the arsenals. If the bolt number is
not in the proper location, it may mean that a previous owner found an M2 bolt and M2 magazine and did his own upgrade.
You have a nice looking rifle with the correct 1922M1 Issue type stock.