Hi and welcome here 
Please check it is not coming from GateKeeper, XQuartz is not needed anymore
wiki.synfig.org/Doc:Troubleshoot … fig_on_OSX
synfig.org/cms/en/news/nativ … e-testing/
youtube.com/watch?v=0rXHm_-Ofo0
Don’t forget you could use the latest dev builds 