Can't join my friends coz of "different version"

So has anyone else noticed that if you leave the game or your game crashes you can't join anyone because they have a "different version" of the game?? Unless they too leave and re-open the whole CoD?

Especially lovely if you crash and you want to join the game that you left and then you just can't because now I somehow have a different version of the game from what my friends have...

Have you noticed this bug?