Phone Link Not Syncing Messages

Try this. Empty the messages bin. I had the same issue. When i emptied the recycle bin in the Google messages App, the sync finally worked. So, from now on, when i delete a text message I go to the recycle bin and delete these messages too. Seems to do the trick.   

Your Surface and Pixel are linked but Phone Link is not syncing messages. Start by checking updates in Phone Link on the PC and Link to Windows on the phone. Confirm both are signed in with the same Microsoft account, turned on, online, and on the same Wi-Fi network. On the Pixel, verify that Link to Windows has permission for notifications and messages, and exclude it from battery optimization; battery saver can interrupt synchronization. On Windows, make sure Battery saver is off and Phone Link is allowed to run in the background. If messages still do not arrive, unlink the phone from Link to Windows, remove it from Phone Link, restart both devices, and pair again using the on-screen flow. If a link fails, note app versions and the sync symptom, then submit feedback from Phone Link. Phone Link supports only the default Android profile, not work or multiple profiles.