EDIT:

As many people are quickly going to discover themselves - this update has not fixed the problem. Many players, including myself, are still unable to make any progress on camos for Modern Warfare 2 weapons.

Examples:

1 // 2 // 3 // 4 // 5

Original Post:

An update was released earlier today which addressed an issue where some players were unable to progress #MW2 Weapon Camo challenges after the #MW3 Season 1 update.

Details: http://trello.com/c/6dXl45KC

https://twitter.com/codupdates/status/1744550784161988735