I have this problem on my Healer that runs a sort of "trap" build for his offensive method. If he lays down Wall of Elements, Lightning Splash, and Daedric Mines and then summons the Storm Atronach the Atronach does not appear and thus I waste Ultimate. For whatever reason this happens I do hope it gets fixed...
And no, simply summoning the Atronach first and then laying down the "traps" is not the solution because I usually set up the "traps" and finish up with the Atronach as per pre-battle preparation.
Guildmaster of Power With Numbers in PS4 NA Server's Aldmeri Dominion.
Proud Founder of the Yaysay cult! DOWN WITH THE NAYSAY CULT!! #ToxicRemedy