If you have upgraded to Reason 12 and want to use your existing Reason 11 Suite Favorite Lists, you must manually copy/move them to Reason 12. This is because Reason Suite is a different product than Reason.
Here is how you do that:
macOS
The folders are in your user Library (not the global Library). The user Library folder is hidden by default. To open it, press the Option key while selecting Go from the menu in Finder, and then select Library. Then:
copy/move your '*.favo' files from your user library:
~/Library/Application Support/Propellerhead Software/Reason Suite
and paste/move to:
~/Library/Application Support/Propellerhead Software/Reason
Windows
Copy/move your '*.favo' files from:
%appdata%\Propellerhead Software\Reason Suite
and paste/move to:
%appdata%\Propellerhead Software\Reason