This is what is noted on the Jamstik website regarding compatibility with Studio One's MPE implementation:
*Note: While Studio One 5 now offers support for MPE controllers, its compatibility is limited to VST2 formatted plugins, which excludes our Jamstik Creator software. Studio One's existing MPE implementation does not preserve MIDI channel information, which is used by the Jamstik to distinguish notes and events on different strings.
This blocks the Creator from showing inputs from the correct strings on the fretboard display as well as routing notes from specific strings to the correct per-string samples or accurately replicate hammer-on effects. We're hoping this issue will be resolved in the near future, but in the meantime, you can still utilize MPE functionality of the Jamstik with other 3rd party, MPE-capable plugins that work with Studio One's VST2 format.
Is anyone aware if this has been rectified to work in VST3 format for optimized performance?