PART WONT MESH! - Simulation in part file vs in assembly file.

Hi everyone! Fairly new to SolidWorks and the world of FEA. I am working on the FEA analysis of two main parts, which both mesh in their separate part file. When put into an assembly, part 1 meshes fine, however if part 2 is put into the assembly (even if it is the only part in the assembly) it will not mesh. There are no interactions, no fixtures, forces, and no changes to the geometry. I have tried reducing the global triangle size, putting in mesh controls and the part still fails to mesh inside the assembly. Despite meshing fine in its part file.