579 raindrops available.
Plant needs 1,210 raindrops to level. Water it anyway and hold finger on screen until all available raindrops are used.
Progress bar only shows 307 raindrops used instead of 579 as expected.
Click to dismiss it. Reopen it. Progress bar now shows the correct 579 used.
Bug is repeatable. Just need to water a plant with fewer raindrops than it takes to level the plant but enough raindrops to trigger the quick watering feature by holding your finger down on the water button.