Dropper used with hydroponics tray doesn't completely empty

[ghost]

You transfer  units of the solution.

Using a filled dropper on a hydroponics tray transfers the solution to it, but the dropper remains visibly filled and cannot be refilled until you transfer the "phantom" solution out of it. Doing so prints the message in the title, with the number of units of missing due to the dropper being empty.

[Tokiko1]

Syringes also seem to have odd behaviour with trays.