When this is happening, go into the sense app, settings, My Home, Monitor and see if both phases of power are going up, or if it’s just one. If it’s just one, you might have one of the lines shorted somewhere, including inside shell where the insulation is, to ground. The tank itself can be ground/neutral in a house with copper pipes. If it’s just a short to 1 phase, and the breaker is tied to both phases with a bar, I’ve seen the breaker not trip like it should in a short circuit. You can have an electrician test for shorts.
Also, has an electrician checked the resistance of each element ? This could be caused by a bad element.
How many elements in the water heater ? And are they wired in series or parallel ?
Something is clearly going on with the electrical side. If the elements were on that long, using that much power, the overflow should be leaking water to relieve pressure. Or you have a broken water line somewhere…