Hi Marv, yeah that's normal - 3DM format is the one you should typically use to save your model data while you are working on stuff within MoI, it's the "native" format that will keep everything in the same form as you see it in MoI. Use the other formats like STEP, IGES, or SAT only when you're trying to move your data to a different CAD program.

You may see various slight changes in things when you save to STEP and read it back in again, some things in STEP format are slightly different than how MoI itself handles things.

If you use 3DM format for your intermediate working stages it should preserve things exactly how you see them in MoI though.

- Michael