"The company’s president Jimmy Pitaro told journalists: “We generally have not broadcasted the anthem and I don't think there’s going to be any change this year. Our plan going into this year is to not broadcast the anthem”. He added the network had communicated with the league about its decision and said: “Again, there could be changes. It’s somewhat unpredictable what’s going to happen in the world but as of now our plan now is to not broadcast the anthem….[The NFL has] not asked but we proactively just as a courtesy and as good partners let them know what our plans are”.

It did air three performances of “Star Spangled Banner” over the entirety of the network’s coverage, according to ESPN senior vice president of event and studio production Stephanie Druley. In the aftermath of Hurricane Harvey, after the mass shooting in Las Vegas which resulted in 58 dead, and after Donald Trump’s comments on players kneeling during the national anthem."

This was pulled from one of many articles that explain that they only air the national anthem at certain times. Yet another article:

Indeed, ESPN Senior Vice President for Event & Studio Production Stephanie Druley reiterated that it “has always been our standing operating procedure” to show the national anthem ceremony only when it occurs in conjunction with something else newsworthy (e.g., a moment of silence to honor victims of tragedies):

She explained the network only aired the anthem three times last year when athletes were protesting because of simultaneous news events — a moment of silence for a hurricane, a moment of silence for the Las Vegas shooting and at the Dallas vs. Arizona game.

So this is nothing new.