We're sorry for the experience. Can we trouble you to perform following troubleshooting steps?
1. Soft Reset the device - Hold the Power button and Volume Down button simultaneously - While holding both of the buttons, the device will automatically restart - You can release the buttons once the phone prompt with the Samsung logo after the phone is already turned on.
2. Check signal reception - Monitor if your text messages keep failing to send in a particular area only. If it is, make sure to find a place with good coverage before sending it.
3. Check message center number - Check whether or not the device has the correct Message Center Number. You may reconfirm the Message Center Number with your service provider. - Open Message App > 3 dots (top right) > Settings > More settings > Text messages > Tap Message center.
4. Clear messaging app cache and data - Go to Settings > Apps > Look for the appropriate app (Messages) > Storage> Clear Cache
We would like to propose a Smart Tutor service if the issue persists. This is a service where we can connect to your device. We can view and access your screen from our side. The advantage is that we will be able to assist you with further troubleshooting over the call. Please contact our Samsung Care Line 1800-4252997 (Mon-Sun -including Public Holidays - 24 hours) regarding this service. Our experts at Samsung Care Line will advise you more in detail.
I know this is a bit old now, but I went though this same issue, except with only one contact (that I was aware of). I assume you have probably resolved this, but maybe this will help the next person. I went through all the steps I could find to resolve it, before I contacted my carrier, and even they had no solution. Tried Samsung Messenger, Google Messenger, Signal - all the same, I could send but couldn't receive messages. Calls worked fine. For an unrelated reason, I turned on "chat features" in Google Messenger, which I hadn't turned on after the update. Suddenly, all my previously unreceived messages came through at once. No issues since. I don't know why this worked, and I'd still like to, but this is what solved it for me.
