I'm updating some of the views for a Live Activity, now that CarPlay can display Live Activities in iOS 26. My Activity is updated only with local updates from the iPhone (no push notifications), displaying a user's blood glucose.
The activity updates fine in both CarPlay and in the Apple Watch Smart Stack, but in CarPlay, the previous values are not cleared when the new values are displayed, resulting in superimposed text and making it essentially unreadable. This only happens when the iPhone screen is off. As soon as the phone screen is woken up, even if the phone is not unlocked, the old values disappear and the display looks fine.
I can't find anything in the API about clearing a display, so I'm wondering if this is a bug (especially since it clears when waking the phone screen). I'm running iOS 26.0.1 on my test phone.
Thanks for any thoughts!