The SOLO button on Channel Strip 2 works by cutting the output of all other Channel Strip 2 plug-ins in the DAW session. It doesn't directly control your DAW's solos.
The best way to use the SOLO feature is to place an instance of Channel Strip 2 onto all the tracks in your DAW session, ensuring to use the SOLO SAFE button is engaged on Channel Strip 2 plug-ins that are inserted on Auxes/Busses/Sub Groups. This will then enable you to use SOLO as intended.
Please note: You need to have installed SSL 360° v1.1 or above to use this feature.