At the moment we have this scenario:
Old machine:
TheMugs profile & save = crash
BigAnt profile & save = no crash
Copy of TheMug to BigAnt profile then back to TheMug = crash
Newer machine:
TheMugs profile & save = no crash
BigAnt profile & save = no crash
Copy of TheMug to BigAnt profile then back to TheMug = no crash
Dev kit:
TheMugs profile & save = no crash
BigAnt profile & save = no crash
Copy of TheMug to BigAnt profile then back to TheMug = no crash
We have done literally hundreds of tests, online, offline, simulate, don't simulate, cloud, no cloud, etc etc
We continue to work on this, at this stage it looks like the dominant factors are a combination of profile and machine.
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Please remember that we cannot test on retail, only MS can do that, we are flying quite blind.