It's a mistake in design. It IS someone still loading. To prove that just check if in your team someone is still showing an icon of a hero of the opposing faction, or if none are like this, ask the enemy team to check that. While someone is loading their icons show heroes from the opposing faction.
And don't underestimate the loading time, or a CTD from the person who was loading, which may take a long time to be processed (this is probably the case when you wait a lot, and then suddenly someone leaves, which was the guy who CTDed but the game took forever to process that)
RogueZeroRendar is correct. It happens on HvV all the time. I'm sure that asking DICE to fix this will only lead to Palpatine being overpowered again.
