I opened a stp model and see spikes and extensions of the material that should not be there. The same model when opened with edrawings does not have any spikes or extra surfaces. I have tried changing import options, vertex welding values, and preference settings to try to alleviate the problem. View at left is the part opened with Composer, and the one at right with edrawings. I have opened the same stp model using Composer 2018 & 2019 with identical results. Not sure what software created the stp file initially (it came from an outside contractor).