[TheMoonbeam]

Installed Windows Mobile Build 10512 yesterday. It was running okay, but thought I'd do a reset today to try running a "clean experience". I've noticed that my main account which is tied to the phone isn't up-to-date, and when I try to sync the account it just sits "syncing" forever (let it sit for an hour and nothing seemed to change). Once or twice it would start updating the threads in Messenger (but not nearly as fast as WP8/8.1 does). Tried restarting the device several times, and still nothing. Messenger is setup to retrieve messages from "Anytime", and after several hours of trying sync my account, it still says "not up to date". Is anyone else running into this issue?

SOLVED!

Shortly after posting this I had an idea, which seems to have resolved the issue. Don't use the People App to sync, it doesn't seem to do a very good job of it, and has a habit of getting stuck while syncing. Instead, open up the email account tied to your phone, and press "sync". Every few minutes it will time-out and show an error message. Just hit "okay" and then hit the sync button again. If you switch over to Messenger, you'll see it updating. Still a bit slower than in WP8/8.1, but it works (which is what counts)!

Honestly, I think Messenger needs it's own sync option, which could continue syncing until either a) the user cancel the sync process, or b) the process completes, or c) it hasn't completed but it's no longer pulling new messages (i.e. if data/wifi connection is lost). I'll post this feedback in the Insider App shortly. :)