My messages say sending forever even though I have full signal

Full bars does not always mean working data, especially on crowded networks. Quick test: open a webpage on mobile data with wifi off. If that is slow too, it is your connection. If the web is fine but only chat hangs, restart the app and check it has background data permission turned on.

If it is account related, turning on two factor while you are in there is always worth it.

Same here, glad someone finally asked this one.

Adding to the accepted answer: results vary a bit by phone and OS version.

Toggle airplane mode for ten seconds, that forces a fresh handshake with the tower and clears stuck-sending nine times out of ten for me.

If it is account related, turning on two factor while you are in there is always worth it.

This is exactly why I read the forum before touching settings, thanks all.

Appreciate the clear explanation above, that finally makes sense to me.

This is exactly why I read the forum before touching settings, thanks all.

Older phone here and the permissions reset fixed it, give that a go.