Agreed with @Edison517, it feels like its just not turning off, but if that were the case, you would be boiling a lot of water and should hear the tank venting (let alone see the flood).
If you aren’t using Solar, you get the Flex sensors and use Dedicated Circuit Monitoring to monitor the hot water circuit.
You would then be able to download hourly data from the Sense and with confidence, point at the Hot Water line.
Another lower tech solution (kinda). Do you have any Nest/Arlo/camera systems that you could point one at the hot water heater to show that the heating element lights don’t turn off? No logging other than a video that you can say “see, it never turns off, how can you say its working properly” even without the exact power draw.