Dupes stuck - resources disappeared - dying fast...

Not exactly a bug, but an undesirable situation due to the fact that duplicants can't walk long distances whey they are underwater. If you make the "move to location" command you notice the icon will turn red before reaching the ladder.

In this particular case, all duplicants are trapped because they can't reach the ladder, making all resources beneath the ladder being marked as unreachable. 

What you can do in this case is to dig a tile of raw mineral (here, sandstone) to make a 1 tile ladder just 1 tile above ground (so they can climb it) halfway between the ladder and where duplicants are, this will make the big ladder reachable again and save your duplicants.

...Or devs could make duplicants swim...

I would note for the devs, however, that the "food shortage" alert (which happened to me today) should be "food out of reach"  or something similar when this sort of thing happens. Food shortage should be restricted to an actual absence of food due to spoilage or failure to produce IMO.