It had to my trying to support Android 5+ "priority" notification mode, where a notification only gets through if sent by a "starred" contact.
And it had an unfortunate side effect, a crash if there was a bunch of old unread messages (beyond what's visible in the app) or if the user enabled "privacy" in AquaMail notification settings.
My code was suppressing the crash, but the code which to actually post the notification was getting skipped.
Ironic: I can't get this "priority" notification mode to work for me, even in Gmail
About to post the fix to Play as 1.6.0.8, many thanks to all for the reports and the testing.