@Steve Whitcher I'm using Canary, but no it hasn't happen to me. I use inprivate often for email because it doesn't leave the login hanging for my emails if I forget to do a clear browser history. I never had any problems with it. So it could be just a Edge Dev thing?
Once I enable that flag and restart the browser, I can no longer start an InPrivate window without the browser crashing. Revert only that flag back to default, restart browser, and InPrivate windows work fine again.