Thunder Shield Didn't Drop

[RainbowRuby]

So i got a decent run going, finally got to Astrolab for the first time(died there but still, its progress), killed 2 Defenders and...the blueprint didnt drop from either of them. the wiki says its a 100% drop chance so im a little confused

[Hodman]

I don't remember being 100% chance to drop, if you take the hunter's grenade it'll be 100% for sure.

[kermat_]

100% means there's 100% chance that one of the defenders in the biome will drop the blueprint
50% means there's a coinflip that one of them will drop the blueprint, so you might need to return there if you're unlucky
etc.

So it doesn't mean that killing a defender gives you 100% chance to get the blueprint.