Unable to purchase Partial Rune Codex

I am trying to farm for the Maw mount and as stated above cannot see this item to purchase from Ven’ari. I put in a ticket and was requested to submit a bug report and also come here to these forums as the Game Masters cannot help. I have already purchased one on my hunter, so wondered if that was causing the issue with my druid. I wanted to swap to her as farming the stygia nexus is so frustrating! I have opened the chest and have the crumbling stele, so am basically stuck now. Can you please help me and I will continuw to farm the silver and dust in the meantime.
TIA

Hello Earnan,

These forums are primarily to provide assistance with our Classic Games Tech (Diablo II, Starcraft, etc…). As your question is more related to World of Warcraft, it would best asked on that forum.

Thanks!