The Textra 'new message icon' in the status bar, should remain to indicate unread messages in the inbox, even after swiping them off your:

• lock screen
• home screen
• notifications (down swiping the status bar)

(unless you've marked it as read of course)

Never had any trouble on previous devices like Samsung S2 or Alpha, but on Edge 7, I've been missing many messages, (even with the Show until dismissed setting) because they accidentally get swiped in pocket, during other activity and nothing indicates new messages, unless you manually go to your inbox to check.

Paid version.

Thanks.