This has been an issue for at least 2 years.
I have a Motorola Razr Maxx HD. This is actually my second one and this problem happened on both phones. I've had this issue on the stock text app and on other messaging apps, so I suspect Verizon is the problem. I've opened up the app info and deleted both the cache and the data and am still having problems.
The problem is that I am not getting all of the text messages being sent to me. Sometimes they come hours later, some times they don't come at all. I can tell I'm missing them because in texts with multiple recipients, I'll see texts that don't make sense because I'm missing a previous text. Or I'll get asked why I didn't respond to a text when the reason is that I never received it.
Another problem, likely related, is that the number on the icon, indicating the number of unread texts, is often wrong. It will tell me I have unread texts, but when I open the app, there are no unread texts.
I've seen many people complain about this online, but I've not seen any solution.
The incorrect number of texts happens when you access those messages from another device rather than the device with the number that the message was sent to. You haven't actually checked the message on that device. Just like when you use a browser extension with an app.....you are reading and responding to the messages via PC, so the interaction is there, just not on the actual main device.
Thanks for the reply, Snn5, however, this is the ONLY device that I use to access my text messages. I don't even know how to access my messages from another device.