MC 1.12.1, Forge 14.22.02463, V-Tweaks 1.4.11.4, Gamemode SSP

After setting this switch to false the witherboss can be summoned.

And the nether??? It didn't spawn in the nether. That was the problem.

That’s because the config says:
Prevent Overworld Witherboss

True prevents summoning.

@oitsjustjose: It did not spawn in the NETHER which is not Overworld. After setting the switch to false it did spawn in both overworld and nether. Your setting prevents the wither boss also in the nether which is a problem.

Not sure how I missed it actually. Thanks!

Yup, I get it. I'll fix it in a bit :)

Thank you.