ID 493719 - Relationship connections with elbows are not preserved when saving and/or loading.

Problem summary
Relationship connections with elbows are not preserved when saving and/or loading.
Customer reported version
modo.15.1v2
Customer reported platform
windows10
Steps to reproduce
1) Open Modo and go to the Setup layout.
2) Create a simple Cube Primitive and drag it into the Schematic viewport.
3) Inside fo the Schematic viewport select Add... and add a Surface Particle Generator.
4) Link the output of the Cube to the Input of the Surface Particle Generator.

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5) Right-click the connect and select Add Elbow.

6) Save and close the scene file. Re-open it and notice that this elbow is orphaned and hasn't been preserved in the connection.​

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Expected behaviour
The scene should open in the same state it was saved in.
Actual behaviour
The elbow connection has not been preserved.
Workaround
Unknown. 
Reproduced by support
This bug has been reproduced in:
15.1v2 - Windows 10
15.0v1 - Windows 10
14.2v1 - Windows 10
14.1v1 - Windows 10
14.0v1 - Windows 10
13.0v1 - Windows 10 -regression
Unable to reproduce bug in:
12.2v2 - Windows 10
Earliest version tested
12.2v2 - This issue doesn't appear in this version and has regressed.