X2Pro Unexpectedly Quits after Starting Conversion

Could you trying deleting X2Pro and redownloading it from the Appstore? When you say inspecting the file, is this when X2Pro is opening and selecting the fcpxml or just after you hit start?

I upgraded to v 4.5.10 and now when I start the conversion the app quits after inspecting the file. I've tried XML 1.10 and 1.9 from FCP and still same problem