I swear, I've done it right and tried to correct it, but B16 seems to have a problem with Item Cellars.
Now, how I have my room set up is that a map appears when you defeat all the enemies. Next, I made the Item cellar, which you open via push block. Link goes down, and... ends up stuck in the floor, is if he entered a cave. I've even set it up just like it is in 1st_example, but it still didn't work.
I was just playing my quest on beta 16 earlier and had no problem with those screens. Double check your warp type, make sure you are using the proper screen and that you are also on the correct map, and make sure the blue square wasn't moved. I am guessing that it's still at your end.
OK, never mind. Turns out some Dmap flags don't automatically turn off for a default dungeon. However, I don't know why you'd want all of them are checked in both Dmaps when you start a new quest, because most questers start the second Dmap as a dungeon, anyways.