Now that GIMP has done a major revision, it seems the 32-bit Windows builds are broken again. This happened the last major revision as well and took weeks to resolve. I should have tested it thoroughly before pushing it out. So, GIMP Portable 2.10.0-2, like the 32-bit local install, is basically useless as you can't import, export, or save files. Our choices are:
1. Wait for the GIMP 2.10.2 Windows builds to be posted. This new version was released yesterday. A 64-bit Windows build should follow soon and then the 32-bit build after that. It should be noted that the 32-bit Windows build could still be broken.
2. Update GIMP Portable to the 64-bit build
3. Revert GIMP Portable to the last fully working previous version until the broken 2.10 builds are fully sorted
I'm leaning towards reverting myself.