Bug? Mana Potions have no effect anymore

Hello,
i played DD for hours. But after i played the first mission at "Double Doom" the mana potions lost their effect.
I can use a potion but the mana won't recover. I tested different maps, with different character types. But the effect is
still the same. I can recover mana by discovering the map but not by consuming potions.
That makes the boss battles a little harder
What can i do? i need some mana
Best regards
Fabio
i played DD for hours. But after i played the first mission at "Double Doom" the mana potions lost their effect.
I can use a potion but the mana won't recover. I tested different maps, with different character types. But the effect is
still the same. I can recover mana by discovering the map but not by consuming potions.
That makes the boss battles a little harder

What can i do? i need some mana

Best regards
Fabio