First, no complaints. Your model is visually just like the images of the Brian Campbell dodecahedron. Beautiful. I used Rhino 6 to check the mesh and run repairs. The geometry has caused the common problem of non-manifold edges and some other issues which mostly resolved through the repair wizard. I finished by converting the model in Meshmixer into a solid which then imported without issue into Anycubic's Slicing software. Odd method but it works for me! Yes, scale. I often double check import sizes as different programs seem to fix different units so decimal points can jump around. I predicted that the finish size on the 'circular' plan view would be 68.7mm ( hence the 1000 re- scale) so a meter to mm unit error. I now hold a very nice resin print which once held just adds to the mystery of these things! Thank you.

Good looking model but it is correct to say that it is not 'print ready'. It will take some work to correct the .obj or .stl mesh to get it print ready. I also found that the scale was not 1:1 and had to enlarge by 1000% to get it to a size I guessed was correct. That said, it's a fun project so the work and research is all part of the process.