I'm trying to transfer LiquidFuel and Oxidizer between a pair of tanks in KSP on my mac. I've previously done this on Windows and Linux machines by Alt+right clicking on each of the two tanks, and then using the 'In' and 'Out" buttons to control the fuel transfer.
However, when I try this (by using the 'alt/option' key on my macbook's keyboard), I just see two small info boxes pop up, each showing the amount of Oxidizer and LiquidFuel, but without any options for transferring in and out.
If it's relevant, I've selected 'Hard' mode for my career.
Has the latest update removed the ability to transfer fuel? Or is this a keybinding issue?