Stock messaging app issues

[Bridget Booth]

Has anyone else noticed the stock messaging app indicating an error with a sent message when no error actually occurred? I don't know any other TMoUS subscribers having a text issue. The spouse's phone is the only one of the three S7s having this problem, but the other two in the house are using Textra. The spouse is stubborn, so switching to Textra or similar won't happen, despite me having spent years trying to get him to switch. Anyway, I restarted his phone, cleared the cache partition, and it stopped doing it for a few hours. When it started back up, I did a factory reset. A few hours later, the errors were showing up. Again, the messages are going through to the recipient without issue. I called customer care. They said they were having switch issues, which would explain all of it including why it seems to just be him. Well, it would explain it if this weren't an ongoing problem for several weeks. They'll replace the phone if the problem persists throughout the weekend, but I'd rather see if there's other troubleshooting tips you fine folks can offer first.