Downloading contacts from paired iPhone 12 to at&t cordless handset

Did you read clear through the Bluetooth instructions starting on page 15 of the manual found here? I didn't see any mention of iPhones, but if you have a Bluetooth connection and have confirmed that connection I'm not sure why it wouldn't work.  Does downloading flash when starting the process?

Yes, I read through the 159 page manual; looked at FAQs; and Troubleshooting. The handset and iPhone are both showing as paired and when I menu through to “Download DIR” the iPhone is listed under “Select device.” Downloading… flashes a few times (as though it is in fact doing so) then the display shows Entries added: 0

Hoping someone can actually troubleshoot this issue or provide a work around.

I'd say your best bet is to call the number in the front of the manual since it's not working as advertised. Page 129 under trouble shooting address it, but not sure it will help you. I really doubt anyone on this forum is familiar enough with this issue to help or not, we can only hope. If everything is indicating you're paired than I have no answer. The trouble shooting section same page also states if it won't download via Bluetooth that you can send the directory from your cell phone. Have you tried that option?

I’ll take your advice and call. Thanks!