Well, most of the nesting material in Box1 is still there.
The trouble is, at this time of year our bluetits spend a lot of time appearing to be busy, but in fact doing not a lot. It's almost as though they have found their nest site and want to make sure some other bird doesn't try to grab it, but it's too early to get on with breeding. So they fuss about, taking stuff into the box and then taking it out again. In the past, I have seen a complete nest built from scratch in a couple of days, so it can be done rapidly when necessary!