ANSYS products can be annoying at times. SolidWorks and DesignModeler share a common geometry kernel, Parasolid, while SpaceClaim uses the ACIS geometry kernel. That means when you move geometry from SW to DM, there is no translation of the geometry, only a transfer. But moving geometry from DM or SW to SC means that the geometry data has to be translated from one kernel to a different kernel, and this is where subtle differences in the internal representation of the geometry can cause very small changes that can have a big effect. See this example.
Another annoying behavior of ANSYS products is that when you have a Mechanical model built on DM geometry, and you open the geometry in SC, all the Mechanical model entities scoped to geometry are broken. You saw that and suffered the time required to reattach the geometry to the entities. After all that effort, the model didn't solve. Maybe you made a mistake in the model build, or maybe it won't solve because of a subtle change in the geometry. I don't have time right now to repeat what you have done moving the DM model to SC, but if you need help getting a parametric version of your geometry solving, I can take a look at that sometime this week.