Summoner problems?

Is there a limit to amount of minions you can have out?

I have enough mana atm to cast
4 fire Ele
Lvl 4 spec ele
1 earth ele
1 storn ele

When try to summon all only 6/7 stay out, when try to cast the 7th one other dies

There’s no limit to the minions one can control, except for the practical limit of the power pool.
Perhaps your total power does not suffice to maintain them all?