Yeah, the tablet runs Fully Kiosk and I tried the same thing with the battery percentage thing and ran into the same issue, so I just simplified and made the automation time-based.
The tablet also likes to freeze a few times a day, so I also created an automation that toggles the smart plug power whenever HA loses connection to the tablet for more than 5 seconds, then toggles back to the original state at the start of the automation, which corrects the problem. Until the next time. But hey! It was only $60, so it’s fine.
…in their cabins, into piles of money