I, too, have this issue. I haven't completed the campaign yet but the bits I have done don't show up as being done, I have no score, nothing unlocked, nothing found at all. What I have played so far was a couple of hours here and there over the last few days between multiplayer games. It would appear that, at least in my case, the simple fix of playing multiplayer games does nothing to unlock progress on the campaign. The progress I have made is being saved since I can continue where I left off; and also I can replay missions that have been completed. I guess there will be a fix for this soon, unless anyone has any other insights as to why this problem should be present.
