Dear GM , My char use many elixir lv 5(Wis and Ess , the other is max) but can't have any point . "Fail in use elixir " , "0 level 5" . It's may be error . U can check my account pls !!
Use a Purple Bamboo Leaf with the elixir, it increases the success rate by 120%. Also make sure that you've consumed elixirs 1 ~ 4 or else you will be unable to consume a level 5 elixir.
Actually op is right, theres a bug currently, with elixirs giving 0 excessively many times in a row. I had a lvl 9 strength going +0 more than 5 times in a row, chance. Similar rates with essence elixirs 8-9. Too many to make it coincidental.