Our two work arounds are
1. Since the elevation is from 0, we isolate hangers and move them down to the correct elevation and run report then undo undo and it is back. Pretty simple. It also works better than sections if you have a lot of small areas with different slab elevations.
2. You can export the report to excel, then setup a excel template for your hangers and add a cell for the elevation calculation. At this point you will use excel to make your labels.