I'm having the same issue with my new Instinct. When I go to Main > Settings > Mobile Sync, it says that my Mobile Sync choice is being registered. It's been saying that since yesterday. I was just online with support, and she had me Update the Data Profile. That was supposed to solve the problem, but it hasn't.
Unfortunately resolving issues for Mobile Sync are not quick easy fixes. In Dpeck1234's case we will have to do a ticket on it to send to network engineers to see why it is only synching one way from device to website and not website to device. For Igreemberg and Wheelman the usual fix is to first check to make sure your new phone is registered on your account online. To do this you would log into your account, select Settings and Passwords at the top of the page, then select to "Edit Your Online Profile", and then select the option to "Update or Add" your phone information. The website will send you a text message to your phone and will need to type this in. After doing this you will be logged off and have to log back in. Once you are logged back in, access the Mobile Sync from the website by going to My Online Tools, then selecting Mobile Sync. If all of your contacts are in here you will need to export them out from the website using the Export link at the top. Save them on your desktop in a CVS file. Then Disable the mobile sync, wait approximately 30 seconds and re-enable the mobile sync from the website. After re-enabling the mobile sync check your devices to make sure the Mobile Sync is running on it. If it is, then Import your contacts back into the website by selecting the Import link and using the file you had exported out. After your contacts are loaded back into the website select the "sync now" button at the bottom of the page and the system will start to sync your contacts down to your phone. This can take a bit to go through, and if you do anything with the phone ie. make/receive calls, texting, browsing it will interrupt the sync process.
P.S. It is very important that you export your contacts from the mobile sync website first before doing the disable. As when you disable the mobile sync at the website it deletes the contacts still there and we will be unable to retrieve them.