X2Pro 4.0.17 Update Stuck In a Crash Loop

This is very concerning, thanks for getting in touch. We are looking into it.

It runs on our current systems here, but we are getting hold of a clean OS X install to try it on that in case it's something to do with other software that we have installed on our systems.

Can you please:

1. Explain exactly when it crashes (e.g. on app launch, or when opening an fcpxml)
2. Explain Exactly what happens when it crashes (e.g. app window disappears and a new window appears containing a crash report)
3. If a crash report window appears, make sure you click the "Send to Apple" button, and tell us what time (and time zone) it crashed.

I updated to the latest version last evening and the app is caught in a crash loop and won't start or load. Issue is you can't revert back to working previous version in app stored. I have a MacBook Pro with Sierra.