This is growing MCU problem. Because if this, I think we'll see a popularity drop off after Avengers 4.
It was very frustrating...and it ruined the movie for me. The movie is really all about what Ant-Man did during his few seconds of screen time during very loud, busy, and hard to follow battle scenes. Like, the whole conflict of the movie (he's under house arrest and must constantly avoid the Feds, to the point of leaving during crucial scenes) is about the consequences of those cameos. That feels like the bigger issue than Ghost, who is a weak as water villain who listens to reason, has a sympathetic cause, and is almost casually dealt with at the end.
In fact, the movie's actual ending is a cliffhanger linking us into the end of Infinity War!