Ok, so the Toxic Spirit should be in the market for you for sure. Can you double (triple!) check again in the Nature / ALL tab or Animals tab and go right to the end. If it's not there for you I'll have to check with S8 whether it's supposed to be there or not. I can't imagine it was limited to when the story was released given it's a gem item.
Ok, leave that with me. I've raised this with the team and will get back to you as soon as I hear back.