Sync 3.4. 21020 is reported to have some bugs with CP, AA, and SiriusXM and Travel Link. There is a thread on this forum outlining the issue.
I would advise you update to the latest version, Sync 3.4.21265. Use the Syn3 Updater to update the Sync app only, autoinstall mode. Also, update your phone to the latest IOS 15.1. This combination works fine on my 2015 F-150 with Sync 3 retrofit.