Our problem is caused because the anchor point change is rendered after the 3D move. We'll need to use Composition Nesting (using a composition as a layer) to feed our current comp a door with the anchor point already set on the desired hinge. We could start over and make a new comp and drag the door in, but After Effects provides us with the Pre-compose command to do this on-the-fly. The Pre-compose command effectively sends current layers to newly created compositions in the past. This page discusses some approaches and options that make the process more difficult than necessary.

Below is the Pre-compose Window. To Pre-compose, select the layer or layers you want in the new comp and choose Layer > Pre-compose from the menu. You can do this quicker by using com-shift-c (thumb on command; little finger on shift; index on c!). The top option, Leave all attributes, will leave the 3D effect (if it is still present) in the current comp and just send the chosen layer(s) to the new comp. This comp is the same size as the layer.

The next task is to align the door layer so that the hinge of the door is at the anchor point of the original parent. There are 2 ways of doing this. One way is to move the door layer in the pre-comp until door is aligned in the parent comp. An easier way is to move the anchor point to the door hinge in the door layer window, as shown below. Either way the pre-comp is too small because the door get cut off in the original composition.

To fix the cut-off we'll need to change the size of the comp, shown below. Unfortunately, when we do this layer stays in the upper left hand corner, so we have to align the door by hand.

To avoid resizing the pre-comp you need to choose "Move all attributes" when pre-composing. This makes the pre-comp the same size as the parent comp. You might then use the Pan Behind/Anchor tool to change the anchor point location from the pre-comp window. But the door's apparent position remains unchanged because the tool makes a corresponding change to the position value, as shown below. A simpler method would be to change the anchor point in the door's layer window, a shown in the next page.

A quick way to align the door layer in the new comp is to Pre-compose (either option), then make the new composition twice the width of the layer. That way you can quickly move the layer to the right edge, which aligns the door in the parent comp. If the door layer is on top, this limits the door to opening to the inside only. If the door is to swing out, the pre-comp needs to be taller not just wider, as shown below.