I no longer get the 'D' checkmark icon that used to come up when a text message was successfully delivered to another Verizon phone. I now just get the regular checkmark icon without the 'D'. This started happening sometime between 9/15 and 9/20.

Has anyone else had this problem? Is there a fix?

There are several threads going on this topic. Here is the one I have been responding to.
Verizon SMS changes?