Yeah there's something weird going on with recent releases, in both NWJS and C3. If I use the newer C3 releases it just closes after it opens up.
If I go back to NWJS 56.1 and C3 r264, without updating either, it works fine.
Strangely, I think sometimes the newer C3 releases work but not every day, so I have to manually edit my .c3p to pretend it was saved in an earlier version.