Lil'Kim, for two weeks before the summit, was mocking the US. You can't sabotage what was already going to fail. They had no intention of giving up anything. We moved a carrier group out of the area, stopped war games with South Korea, got South Korea to lift some sanctions, and even gave them talking points on Otto Warmbier's death.
In return, they shut down one already damaged testing facility (and opened up new ones in its place) and returned some war dead.
North Korea had no reason to give in to anything at this summit. They got more than they did with Madeline Albright and Bill Clinton.