Another attempt at a fix for #1094

[Yive]

This is terrible and increases the CPU load due to having to loop over the inventory up to two times if the event was cancelled.

That being said though, I wasn't able to have issues when fix-stack was set to true or false.

If this doesn't get merged, I recommend reverting my previous attempt as that causes more issues than it fixes. Overall this is just a hacky fix until a better solution is found. Unfortunately I don't understand this plugin enough to provide one.