TIER & DRIVING SINCE keeps disappearing why?

Everyday I log on My Tier and Driving since isn’t there sometimes it is but most of the time it’s not. When I got on Rewards Overview it shows that I’ve been Driving since 2007 and I’m Tier 6. What is going on can someone please explain this to me?

The answer you seek is contained in this thread -http://forums.forzamotorsport.net/turn10_postst167_New-forums-FAQ-and-How-To.aspx