iPhone shows only last message in a thread delivered

Hello JOHN1-,

To help us get a better understanding of the issue, we’d like to ask a few questions.

1. Does this happen with all conversations and threads, or does it only happen with certain contacts?

2. Do the other messages ever show an error, such as "Not Delivered"?

3. Do you use Messages in iCloud? If so, do the messages show as being delivered on other devices?

The above information will help us plan how to proceed.

Please also check out the information in this link on sending messages, which may help: Send and reply to messages on iPhone

Send a text message

You can send a text message to one or more people to start a new conversation.

1. Open the Messages app .

2. Tap  at the top of the screen.

3. Enter the phone number, contact name, or Apple ID of each recipient.

4. Or tap , then choose contacts from the list.

5. Note: If your iPhone is set up with Dual SIM, you can also tap your number to switch to your other outgoing line.

6. Tap the text field above the keyboard, then type your message, or tap  to dictate text.

7. Tap  to send.

If a message can’t be sent, an alert  appears. Tap the alert to try sending the message again.

You can add photos, videos, or emoji, or access other special features such as animated effects, payments, stickers, songs, and more with iMessage apps.

To return to the Messages list from a conversation, tap .

Thanks!