After placing Stair , using Standard Stair tool or Stair tool, if tried to copy or move, the whole stair object is not copying or moving.
Stair placement tool is a structural object which can be placed using Stair tool. We have three Stair tool
1. Stair2. Extended Stair3. Standard Stair.
After placing you will get Connection geometry. To move the stair, you need to select that connection geometry and then can copy / move the stair. To see that geometry, you need to switch to Wireframe mode presentation
1. For Stair this geometry comes up with Box like below image.
2. For Standard Stair, this comes up as Circle a shown below
So to Copy/Move the Stair, you should always select the Connection geometry which will allow the whole stair to move so. Selecting one element will not copy/move the whole stair.