This is what happens to me...
I get the black bear skins, grizzly skins and pronghorn skins before going to see him at the geothermal park. Then at the part where you go back to the lab, he says "sorry but I can't continue until I have all the ingredients" (even though I have them all already) and they are gone from the inventory. But at this point I just pick up the angel bait sample from his desk, and the mission continues.
So maybe that's what is happening to you too?
(If the angel bait sample isn't there try talking to him again and see if it appears).