CCs,
Honestly, being I am not a chemist or doctor. it's hard to say if those ingredients hurt the yield. I do know that the manufacturers of many of these products use the alchohol based additives to saturate and penetrate the scalp to deliver the active ingredient (minoxidil) to the hair follicles. What level of toxicity the inactive ingredients caused is really unknown.
But if you really want to know for sure, you could always have a scalp biopsy done to see if any of the transplanted folicles were damaged, and to see if they are still there. I don't want to start a big controversy here, but you'll often see me preach to patients to wait a full year between procedures. WHY? Part of the risk when you go back too early is transection of the exisiting hair follicles. So if new recipient incisions are made on top of an area that still has some yield coming through, transection can and will occur. That's my opinion and I have seen it happen before, but again we don't know for sure if that is why your yield is lacking.
You did not have this problem the first time because there were no previously transplanted hidden follicles below the surface to damage. But it's usually the guys that are late bloomers that may go back too early. In other words, they don't see the result "they want to see" post-op from the first procedure so they rush back in and have another one done to boost density. In many cases they are not told about the potential of transection. Still, we don't know for sure that is "your" situation unless you have the biopsies done. A local derm could do it for you.
And it also would not hurt to get some other opinions like Optimist suggested.