Sophos Secure Mail not opening on iOS devices.

We've had several iOS devices in the last two days where users are complaining that after they enter their password, they just get the rotating circle and "Please wait."  It continues for a long time and then app seems to close.

Restarting the device doesn't seem to help all the time.

Trouble at home and at the office.  Tried with wifi on and off.  Confirmed user can get to websites.  Both are Sprint users, if that makes any difference.

Any idea what could be causing this and how to fix it.  A secure mail app is no good if users can't access their mail/calendar/contacts when they need to.