Hi
So, this is likely some GL state being enabled by ofMesh which once used, doesnt disable that state to whatever it was previously, and Syphon’s draw code dislikes the ‘leaked’ state of ofMesh.
Typically, for middle ware like Syphon, one really wants to have set, known state prior to your code, and then middle ware returns it to that state.
I suspect something similar is happening. Look at the source of ofMesh and investigate the state changes in GL, and ensure you set things back to disabled, or prior state.