Since the same thing happens in champions (though mostly only with the skirt options) I'd say its a cryptic thing. Its just that the game doesn't fully load every player in the zone when you beam in, as such it can take a bit longer sometimes and the uniform appears to fade in when you first see it.
unless of course you can sit at a distance and not see the uniform properly for an extended period of time and then I'd say you have a different problem.
I have this issue all the time. Anytime my character or one of my BOffs wear the TOS skirt it does this as soon as I start zooming out. I don't even have to be all the way zoomed out. And to make things worse it doesn't go away after a a few seconds, it will stay that way for the entire mission. Its not that it vanishes, its more like it gets see through lines running horizontally across the entire skirt. Also the boots that they released to go with this seem to be doing the same thing so that the my calves are also showing. Would love to hear a fix for this.