MaxExpansionDepth not respected

[Emp1Motus]

It seems the MaxExpansiondepth is ignored or not working correctly.
Maybe we just misunderstood a concept.
But:
The url http://localhost:7026/ODataApi/ProjectTaskActivityODataApi in the given sample returns no customer details
but http://localhost:7026/ODataApi/ProjectTaskODataApi does.
We are wondering why the third level with customer details is cut off when calling the ProjectTaskActivityODataApi .

Is there an error in our EDM model ?
Is this a bug?
OdataSample.zip

[Emp1Motus]

there has been a misunderstanding on our side.
expand must be called regardless of the supplied data