Thank you for getting back here, @lionhound.

I appreciate you performing the steps provide by my colleague. Since clearing the browser's cache and refreshing QBO does not work. You can also use another supported browser when opening your QBO account to see the Send a reminder button.

However, if the issue persists, I highly recommend reaching out to our technical support team. They use specific tools to check your account and can also start screen-sharing sessions to further investigate the root cause of the issue. Here's how to connect with them:

1. Go to the Help menu and select Contact Us.
2. In the What can we help you with? field, enter Need to send contractors an email reminder for W9.
3. Then, click Continue.
4. Choose either Chat with us or Have us call you. 

For your reference, please see this article: Invite a contractor to add their own tax info. 

Then, to guide your contractors in adding their info, you can direct them to this link: Fill out a W-9 and view your 1099-MISC in QuickBooks Self-Employed. 

Let me know how this goes and leave a reply below if you need further assistance managing your contractors. I'm always around to help. Have a good one.