'could not send' notification doesn't go away.

[MrGolbs]

Hey, new here.
Not sure if this is in the right place, but I do have a Z1 Compact.
I have a problem that when an sms doesn't send, I get the could not send notification with the messaging icon but red and sad faced.
This notification doesn't go away when the message is sent or deleted.
The only way I've found to get rid of it is to delete the entire conversation which I don't want to be doing.

I hope someone can help me with this.
Thanks, J

 

[Sizzln]

I've got the same issue. Mine only came up when I tried sending a MMS with two pictures attached. It said "could not send" and failed to send the message. Then the red notification envelope came up in my notifications.
I can clear it, but when I go into my messages the contacts name has the red envelope next to them. Even if I clear the failed message it stays next to their name. Then the next time I send a text I get the notification come back up on my home screen.
The only way to get rid of it is as MrGolbs said, to clear the whole conversation, which isn't ideal. I've checked other forums and found nothing. If i send just one picture message, its fine. Send two and it fails.
I've tried clearing the cache, in settings, i have the delivery reports box checked, in developer options i have the dont keep activities box checked, but it did not help.
Any help would be gratefully appreciated.