Wow imagine, still a problem in C3D 2022.
IME Acad does not like creating hatches through xref's. If the xref has the geometry required for the hatch then use NCopy (NC) to bring it into your file or copy/paste. Unload the xref's and hatch. Erase the linework if dynamic hatches are not being used to reduce duplicate data. The erased hatch boundaries are easily recreated from the Right-click hatch commands.
John Mayo
Also confirm the boundaries used do not contain pline errors (overlapping objects, null nodes, zero-length geometry, crossing objects) that drive acad hatches and their creators nuts. 🙂 Use Mapclean or create new boundaries with the boundary command.
John Mayo