WhatsApp messages cannot be transferred to computer if the 'End-to-End Encrypted Backup' option is turned on.
When this option is enabled, the messages are securely encrypted and stored on the device, and Tansee does not have access to them.

1. Open WhatsApp on your iPhone and go to Settings - Chats - Chat Backup.
2. Tap 'End-to-End Encrypted Backup'.
3. Tap Turn off, then enter your password or 64-digit encryption key.
4. Tap turn off again to confirm.

Please download and install the latest version of Tansee iPhone Message Transfer for Mac here.

What to Do If Tansee iPhone Message Transfer Does Not Recognize My iPhone?

If you have a large number of apps or photos, Tansee will take longer time reading data.
What to Do If Tansee iPhone Message Transfer Keeps Reading Data?
If asked, unlock your iOS or iPadOS device using your passcode. If you see a prompt on your iOS or iPadOS device asking you to Trust This Computer, tap Trust to continue.

How to Fix 'Disk is Full' Error?
How to Fix 'This iPhone requires backup files to be encrypted. Enter a password to protect your iPhone backup' Error?
Where Does iTunes Store Backups and How to Find Them?
How to Extract iTunes Backup Files?
How to Uncheck iTunes Backup Password?
How to Reset iTunes Encrypted Backup Password?

Click the button labeled 'Save' located at the bottom of the screen.
You can choose to save all your iPhone, iPad, or iPod messages to your Mac in TFST, TEXT, PDF format.
Select the desired contact from the Tansee contact list, select the messages by date and then click 'Save'.