If there are question marks in the pipe network longitudinal section (profile view) instead of ground-level values, you need to set the reference surface:
You can set the reference surface in the pipe and structure grid view for each and every network individually which can be time-consuming. If you want to save some time, use the iDAS Set Ref Surface command:
Select the networks you want to assign the reference surface to as well as the reference surface:
Result:
