X2Pro instantly crashes when I open my fcpxml.

Hi DP. Sorry that you are experiencing a crash. I think it is because you have an FCPXML that X2Pro considers to be "invalid". We are working on a fix to handle this, but in the meantime there is a tool that you can use to fix your fcpxml so that it doesn't crash X2Pro.

See this forum post:
x2pro.net/help/support-forum/12-x2pro-professional/1390-invalid-track-layout-for-asset.html

Please let us know how you get on with the workaround in there

I use X2Pro Audio Converter version 4.0.12.
I use Final Cut Pro X version 10.3.2.
I use iMac OS X El Capitan version 10.11.6.

I've just converted a fcpxml to AAF using X2Pro Audio Converter with no problems at all, no errors and not even a rapport upon completing the AAF file, so it went smoothly through, but this one just made the program crash instantly and I have checked my video for missing audio or video files but found none, so it should had gone through the converter with no problems. The fcpxml I converted to an AAF file just before this one with problems, had a sign of some missing files, but none big enough for it to make errors or crash, or not making converting the fcpxml to AAF. So this is a real mystery for me and the rapport that follows the crash says it's a:
Crashed Thread: 3 Dispatch queue: MultiThreaded Task Queue
(Going around 1-9 Dispatch queues, so it's not always 3)

Also attaching the fcpxml that went through X2Pro to an AAF file with no problems as well. Cheers!