Hello,
For the sake of community who are wondering what is causing this issue, and as a way of recording as a knowledge for future occurrence -
We had a separate thread on this topic through the ADN channel. We have asked the Revit product team. In the situations like this, possible place to look are:
1) This is sometimes caused by using the wrong overload of NewFamilyIntance().
2) If the result of the non-rounded numbers is a beam whose curve is “slightly off axis”, this could be the source of some trouble. We don't see the numbers, but if the X coordinate changes from something like 1.00046 to 1.000085 or something, that could be the slightly off axis result.
In this specific case, #1 seems to be okay. The customer's investigation suggests #2 is causing the issue.
FYI