Stair or Ladder has more than one related bottom plane.
A stair or ladder has multiple relationships to the bottom plane. The location of the stair or ladder depends on the inputs; therefore, more than one input would make the location of the ladder ambiguous.
It is highly likely that one would not even notice a problem with the behavior of the ladder or stair because the first encountered input would be used, and any additional inputs would be ignored. However, it is plausible that if any of the inputs get modified, the ladder could compute its location based off a different input. The ladder would seem to move around unpredictably.
What You Should Do
Manually update the ladder or stair.
Ask your database administrator to back up the model.
Send the database backup to Hexagon PPM Support.
Open the model.
Select the ladder or stair.
On the ribbon, click Select Bottom Plane .
In a graphic view, select a new bottom plane for the stair or ladder.
Click Finish on the ribbon.