Push completely the tray plate (with the paper) until it stay locked to the lower position and reinsert the tray.
There is green lever inside the tray for adjusting the tray to hold Legal Size paper. Check to see if it was inadvertently adjusted when paper was added to the tray.
Hope this helps.
How does the lever work?
I saw a tab and pressed it and it still didn't work.
Seems you have to hold the lever while putting the drawer back in?
It has gone in now messing with the lever but not clear exactly what worked.