App unexpectedly quits with iOS 10.2 – Avaya one-X® Mobile Preferred for IPO Review

Since upgrading to iOS 10.2, this app no longer works as it unexpectedly quits on launch. If I delete the app and reinstall, it works for a day or less, then quit on launch again.
Review by VernonM on Avaya one-X® Mobile Preferred for IPO.