Recently I ran into an issue with Blender after adding the environment variables PYTHONHOME and PYTHONPATH.

I first didn’t even realize that this might be the issue since they pointed to a version of Python with which Blender claims to be compatible. But of course Blender comes with its own Python versions. Blender still works, but just some of that ‘little’ things are messed up.

So if you ‘re not able to load your Add-Ons or having strange results while exporting models, remember that you may have set these variables.