I'm fairly new to 3d printing. I'll try to get to the problem quickly. I have tried every suggestion I can find, but I'm missing some knowledge. I made a HOLLOW threaded hole in Sketchup that keeps converting to SOLID in a few different slicer softwares I have tried. I have already successfully printed parts like this using the same tool (EP Fasteners & Holes), and they looked and printed hollow. I've tried solid inspector, Netfabb online, Cura, ideaMaker. I even tried to print it anyway and it was printing solid, not hollow. I'm pretty sure my model has a problem, but I just can't figure it out. I could go on, but you get the point. I'm uploading a file that has my part and the threaded hole separately AND a screenshot of the sliced preview. If someone could fix the part, that would be AWESOME! But, I really would like to know how to fix the problem because I'll be doing this type of thing in the future. Help and suggestions would be greatly appreciated.
part7.stl