I've been using Purigen and recharging them for close to a year now. A few comments, although I can't really say anything for sure about your situation because I don't use Amquel...
There is a "caution" on the Purigen instructions that says "... some slime coat products may permanently foul Purigen and render regeneration difficult." Not sure what all is in the "plus" part of the Amquel. On the Seachem Purigen FAQs...
... they specifically say that "amine-based" slime coat products will cause Purigen to become toxic. Soo... best to find out what exactly is in the Amquel. That statement is pretty much why I've always used Seachem dechlorinators like ChlorGuard or Prime.
After I regenerate mine using Prime, there is a funny sulfur smell... but that's the smell of the Prime. Right after regeneration, it's always pure white, but as it dries out some beads will turn somewhat tan. I read somewhere that this is normal when the beads dry out. I think I also remember hearing suggestions that it should be somewhat damp. Some folks leave their recharged bags soaking in RO
water. I just kind of shake out most the water and then seal them up in ziplocs.