Mage - Higher Magic Bug

[landwalker2007]

I am in 2nd and 3rd island normal 42/50 in Grand Straregy, I am using Higher Magic frequently but I found out some bug and seek for help.

Here are my finding:
First round always work (I usually cast FlamingArrow and then FireBall)
2nd round and other rounds sometimes it works, some times does not especially if my first spell is NOT offensive spell. However, I also enocunter the situation there is no chance for me to cast 2nd spell even the 1st spell is offensive spell.

I did TEST the skill by on purposingly DELAY the battle for like 10 to 15 rounds, and each round I can ONLY caster ONE spell after I manage control the enemy (each time I only cast healing to delay the battle)

Anyone encounter similar issue, please.

Thank for your help!