When Dragging Pipe Network Structures you may notice that the Rim Elevation Changes. Sure the Rim elevation will change if set to Surface elevations, but they can change even if the Rim elevation is set manually.
In this example, I was cleaning up an as-built utility plan. I already had the Rim and Sump elevation data from the field entered in, but I lacked the horizontal locations. I recently received the remaining data, so I am adjusting everything accordingly.
If you drag the structure to a Node Osnap, the Rim elevation will change. It may not be the Point elevation value, but it will likely change. I wish I had specific exacting details of how and why, but finding the reason does not justify the time needed.
Instead just drag the structure free to the node location. You should find that the structure Rim and Sump elevations will remain unchanged.