Blue Mage Weekly Challenge (Silver) Bug

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Date & Time: 2019 Nov 15th
Frequency: once
World name: Zalera
Character name: Caimie Tsukino
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Steps:
1. When doing this week's blue mage weekly challenge (silver) - use only unaspected spells OR fire spell, I could not get the achievement even though I used only Tailscrew, Offguard, Mindblast and Song of Torment.
https://i.imgur.com/bc2XGgk.jpg

2. Afterwards, I tried exactly the same way, but added in 1 hit of Flame Thrower, then it worked in getting the achievement. So the "unaspected OR fire" was not true. You actually needed at least 1 strike of fire spell, which is a bug. This needs to be fixed.
https://i.imgur.com/f5dtKXq.jpg