I'm observing exactly the same, except that the workaround of saving the project does NOT work.
Even if I _do_ save the project, a 2Mb only image is written.
I had added about 6Gb wirth of files. When writing finished (in a suspiciously short time), it said it had succesfully written about 3Gb (wrong size) and the _real_ image it has written was 2Mb.
I'm observing exactly the same, except that the workaround of saving the project does NOT work.
Even if I _do_ save the project, a 2Mb only image is written.
I had added about 6Gb wirth of files. When writing finished (in a suspiciously short time), it said it had succesfully written about 3Gb (wrong size) and the _real_ image it has written was 2Mb.