The solution is obvious. In the few seconds you were gone, the bureaucrocs gathered up the things you left and put them in the intake duct of the water cooler, where they were samified and all the imagination drained out and incinerated, and the byproducts repurposed into cups of plain water.
it's part of the bureaucrocs' plan to turn all of Ur grey. In truth, we should be concentrating on fighting them, not the Rook, as they are the bigger threat to imagination.
Well... Subway instances seem to go off and die. However, if somebody happens to board the train before it leaves and dies, the instance will continue to thrive (why sometimes it takes less than 60 seconds before it leaves). I believe that bureaucratic halls sorta rotate. So if you leave something, leave, reenter, you may not see said items. However, if you're lucky, you may enter the same instance, either at that time or way later in the future. GoC instances seem to work like this as well. The instances in the Jeth Tower rooms seem to die once the person leaves. When somebody enters the keyed door, a new instance is created with the related items that respawn. It is also possible every player has their own instance and when they enter, all items are regenerated. Unlikely due to space issues. Never tested. Quest instances seem to work like this, but only testable on The Kid's Room, and only with one chance. Unless staff help.
So if you want to get rid of bags, you can leave them in a subway train.