There is another possibility though: Barb is actually dead and she won’t be returning to Stranger Things season 2.
During the Stranger Things panel at SDCC, the first question put to the cast was “Will Barb be in season 2?”
In season 1 of Stranger Things, Barb (Shannon Purser) was dragged to the Upside Down and unceremoniously killed by the Demogorgon after being left alone by the pool when Nancy left a party with Steve.