Toro Flow Sensor wrong reading

Hello ! i’ve been a rachio user for 3 seasons now. When I got my controller I installed it and calibrated it, all looked good and each zone in my controller reported reasonable numbers (simple math multiplying number of drip emitters * their gph).

Now that we’ve started using the system after the winter I get a constant ~4gpm reading on the app (and the corresponding leak alerts) for all zones. Even when I have the master valve closed, and when I remove the sensor from it’s pvc tee. There’s no flow report if a completely disconnect the sensor wires from the rachio controller.

I tapped into the splice with a multimeter and checked the voltage when I calibrate: it drops differently for zones with different flow profiles (from 27.1v when there’s no flow to 24.7v in a given zone, 25.2v in a different zone, 26.3v in a different zone) yet the app continues to report between 3.9 gpm and 4.1 gpm, no matter what.

How can I debug this further ? Has there been any update in the app or controller that may be affecting my setup ?