The problem is not pixel specific. I have a Pixel XL and ancient Nexus 10 running an older OS version, and their behavior is identical.
I have never seen any correct indication of what is to be watered today on my Android devices. It’s always wrong. It never indicates that anything will be watered today, just shows indicates the one zone is that is watering now.
For fun I took a screenshot of the web interface on a regular PC, and it is also wrong. See “Schedule updates” on the attached screenshot for today (May 6). Note that several zones are listed to be watered today, May 6. Then look at the zones shown in “My Yard”. They do not show any watering scheduled for today.
Seems like this could be fixed pretty easily, but for me, it’s been wrong for months.