unexpected behaviour of aux switch mapped to ‘perform mode’

When you press the perform mode button on the H90 it switches from Select Mode to Perform Mode. When you click again, it toggles between the first 3 assignments of the built in foot switches (P,A,B, FS1-FS3) and the alternate foots witches (P,A,B, but now called FS4-FS6)

However, if you assign an external/aux foot switch to switch to Perform Mode, it does switch to Perform Mode (from Select Mode) when you first press it, but when you press it a second time, nothing happens. It doesn’t switch to FS4-FS6… Is there another method to assign an aux pedal to toggle between the internal foot switch functions FS1-3 and FS4-6?

Or is it the idea that you can tap with your foot on the select and perform and select knop if you want to toggle? (they don’t seem sturdy enough for that)

Hope somebody knows more about this…

Thanks, Daniel