I also have failed texts. I'm using the stock samsung texting app. What fixes it is airplane mode on/off but it's frustrating because this should be a non-issue.
This logic can also be applied to the people complaining about the glass back. Why does it matter if you're just going to slap a case on it? Goes both ways.
I have that spigen one and it works well. Currently looking for a leather one with the cards in the front so I can possibly wireless charge. I also use a magnetic car mount.
So looks like the incident is not isolated to just me and my friend. It's very frustrating because it basically just bricks the phone until it decides to let data through.