I've used this wax for almost 8 years now. I have seen variations in hardness and color over the years. The hardness variability comes with the amount of oil in the wax. You can add a little oil (coconut, mineral, soybean) to the wax to soften it up. I do find that I have to wick up when the wax is harder but I've gotten used to it.
I think the big picture here is that we are working with raw materials, not finished goods. Do you think IGI can send the oil back and say, I'm sorry, this isn't working like the last barrel I got from you, I'm going to need another? They work with it and figure out how to make it into the product they need. It's our job as the crafter to appreciate the challenges they face with their raw materials and work with what we have and accept that there will be variations. A raw material is not going to be consistent, period.
And I'm pretty sure when Yankee gets a tanker truck full of wax they don't just blindly start making product with it, they test it, they probably test the crap out of it so they know exactly how it's going to perform and what changes they need to make to end up with the finished product their customers expect.
There's a big difference from "out of spec" and "feels/looks different". Out of spec means it's not even they product they intended to make. Looks different/feels different means just that, it may be further to one side of the specification which causes the difference in look and feel, but that doesn't mean it's out of spec. And I doubt any supplier in their right mind would try to sell a wax that is out of spec. If they are, shame on them if they're not disclosing it.