weisdaclick Ashley gave you the right answer, Ejecta is not officially supported by Scirra (or me by that matter) is something I shared to the community, everything is 100% working on canvas2D (webGL doesn't work anymore with the new Construct 2 build but I'll release soon an update).
I always said this, Ejecta is not easy to use, it's certainly not a drag and drop solution. Every time I build my game I find some new quirk of Xcode that can take even half an hour to fix sometimes is just better to download Ejecta and start from scratch.
What I would do.
Disable any plugin.
Make sure you are not using tiled backgrounds.
Export with no compression, run exporter.
Download a brand new copy of Ejecta.
Check console for errors and post them here along with the line of code that generated the error.