Yes to all of that. I tried 1.7.1 (on both) too. I even tried launching Mod Kit when only one of them was patched to see if I would at least get an error, but I got the same ****.
I've had it working two days ago. Completely nuked my entire system yesterday because the game wasn't launching (every other game worked fine). Now I got Bannerlord working as it should, but the Modding Kit just won't launch. I tried relocating it to a different SSD, verifying game files...