I have been reporting this through the ingame bug reporting tool, but thought I’d check the forums. On the US forums there are a fair few posts about the issue, but on the EU forums I found none.
The issue:
Those mages who finished the quest “easy win” and learned the tome of polymorph: mosswool before the hot fix are still missing the spell from their spellbook and have no way of getting it again. Please make it so that we can either redo the quest, send us the item in the mail or something to fix it for us.
Much appreciated.