Why are texts being reported as sent but are not delivering to only one contact?

A

AC Question

Texts are being reported as sent but are not delivering to only one contact.

Me: Sony Xperia Z2 and Textra app and standard messaging app
Him: HTC One and Textra app
Neither of my messaging apps change it, I have deleted the text that it stopped delivering on (which was a lot of emojis) and all the texts sent after that.

This has happened to us before and he says that it was emojis that time too (I didn't remember). Last time it just restarted by itself.

I receive his texts to me but he does not receive mine.