Here is the response from Autodesk:
The issue is that the invert elevation uses the hard coded internal z plane which where the project base point and survey point are originally located.
Even though the project base point sets the 0,0,0 point for the project, and in theory moving it vertically (as was done in this project), should change the invert elevation, the invert elevation uses the internal coordinate system.
The startup location (and initial z plane) can be found by going through the following process:
Open a section where the Project Base point is visible.
Unpin it.
Right+click.
Select move to Startup Location.
To fix this issue. Set the Project Base Point on the initial z plane, pin it, and then move everything down the 181’ 8” so that the Ground Level is at 0,0.
The request to have this behavior changed to use the Project base point has already been made with our Development Group, and I have added this case to the one they are aware of so that they know more people are reporting this behavior. Having said that, any change in behavior will require the code for Revit to be modified, and as such, we do not have an immediate fix aside from the workflow I laid out above.
