Question I have assigned my expression pedal to control the guitar level. I can see in the Pedal setup menu the values changing, but these values are not the same as on the mix window.  The maximum volume only goes up to 0dB in the pedal page, while it goes up to a maximum of +24dB in the mix page. Am I loosing 24 dB

It's actually working as intended but with a graphical bug. The max level of the expression pedal and the max level on the mix screen should show the same number, but for the guitar there is a difference of 24 dB. To set the max guitar volume the way you want it, set it on the mix screen. Then, the expression pedal will control the volume up to the level set on the mix screen. Basically, the bug is that +24 guitar on the mix screen is showing as 0db on the exp pedal setup. So, imagine your guitar is set to 11db on the mix screen. The exp pedal max will show -13 db. (24 dB less).