Activation Link Missing in Emails

Hi everyone,

I’m experiencing an issue where the activation link is not being generated in the emails sent from my site. The email is sent successfully, but the placeholder {account_activation_link} remains empty, so the link does not appear in the email.

Here are some useful details:

• The account_secret_hash meta key exists in the database and is correctly associated with users.
• If I manually construct the link using the format https://mysite.com/?act=activate_via_email&hash={hash}&user_id={id}, it works perfectly and activates the account. This suggests the issue is specifically with generating or replacing the placeholder in the email.
• I’ve already disabled all other plugins to rule out conflicts, but the issue persists.
• I’ve disabled the LiteSpeed Cache plugin to ensure caching isn’t affecting the process.
• There is no expiration set for the activation links.

Has anyone faced a similar issue or have suggestions on how to resolve the missing placeholder problem? Could this be a template-specific issue or a misconfiguration with the email sending system?

WP: 6.7.1
PHP: 8.3.13
UM: 2.9.1

Thanks so much for your help!