An audio tech (at a different network) told me it’s not unheard-of for the new generation of digital equipment to have software glitches that would keep a microphone live (or keep it from going live) sometimes. If that were the case, they may have been trying to cut her off unsuccessfully.
And no, live news feeds don’t normally run on delay.
I was under the impression it was good practice to always leave lav mikes on. Otherwise you were relying on the “talent” to remember to turn them back on before they went live again.