I hate to keep bringing this up but I'm still having this issue. I've copied the map to a new vmf file. I've rebuilt all the displacements. I've changed their power to 2,3 and 4. Neither power worked. I've even tried using different materials for the displacements, including dev textures. I've got the "make_triangles:calc_triangle_representation: Cannot convert" down from 8 instances to just 3. So here's an update on other things I've tried. While looking for other potential solutions, I found that BspZip has a '-deletecubemaps' command, which you should run between VRAD and the 'copy file' command. (VBSP > VVIS> VRAD> BspZip (-deletecubemaps) > Copy File > Run TF2) I gave it a try anyway and to not much surprise, it found no cubemaps to delete. I wondered if the issue was due to the amount of custom content I am packing into the map. Usually I use BspZip to pack the content immediately after VRAD has finished, but this time I compiled the map without packing the content. This time I COULD build cubemaps without it crashing! I then attempted to repack the custom content via BspZip and reloaded the map, but was greeted with the "Material <material> does not support vertex format used by the mesh" error from before. Regardless I closed out of the map and attempted to repack it via the 'bsp_repack' command, where surprise surprise, TF2 crashed with the same "Out of Memory" error.