Multiplayer button hud flashes black and cant cast abilities

I can't say that I have, not as you've described, and I frequently play an Elementalist. I've had cases where a press doesn't trigger and I jump instead of casting the aoe, but they're uncommon. It's also just one hop, not a series of them. 

It's probably not a factor, but what system are you on? And do you know if your host status is a factor? Is this more or less likely to happen when you're leader, or does it have no effect?

Sorry, I'm on xbox one and it happens both as host and in someone else's lobby with similar frequency. It seems to happen about half the time I'm trying to cast these aoes, and after some fiddling it happens almost all the time when im pressing the two buttons quickly in sequence (fast enough that the confirm popup barely appears before im hitting 'a') and it also happen if I'm holding down the analog stick in a specific direction while also pressing the buttons. Remapping from a/b/x/y/rb doesn't make any difference to it happening. 

It's very strange, but I know its going to happen (that my character will jump and not activate an ability) becuase all the button maps on the hud flash black. If after the first black flash I try to recast it it only makes me jump and happens all over again, but if I see the first black flash and wait in place for a second black flash (being sure not to move or press any other buttons) I can then slowly reenter the two button sequence and have my character ability work.

Okay:

-Anytime any of my characters is sprinting (L3 depressed) and I stop moving, for a second all my abilities black out and I am unable to cast anything... so I end up jumping.

-Anytime any of my characters is standing comletely still and holding my auto attack down (RT button), when I try to move the character (sprinting or just regular speed) from that standstill auto-attack all my abilities black out and I am unable to cast any AOE type abilities and my character ends up jumping instead.

So is this sprint/movement related thing where abilites black out a bug or something? This should really be addressed as this keeps interfering with my gameplay. Please respond as I'd like to know if there is somewhere else I should report this issue to see it is eventually taken care of. Thanks.