This happens alot to me.Ive only played like 4 games to any extent so far,and this happens multiple times per game to me.

A caster who has the mana,loses the ability to cast spells.

*sometimes the  "cast" bar goes away and doesnt want to come back-reload often fixes this

*sometimes all the spells but raise land and lower land cant be cast,even though i have more than enough mana.Yet for some reason those two can be cast -reload often fixes this.

But there are times, like in this game, my fourth real try at a game,that nothing i do gets the caster back his full casting ability.

So ends game try number 4 for me...........