For me this is an exporter error.
The structure for this file is:
<Group> Cube.001 {
<Dart> { 1 }
.
.
.
}
<Group> Cube {
<Dart> { 1 }
.
.
.
}
and it should be:
<Group> character {
<Dart> { 1 }
<Group> Cube.001 {
.
.
.
}
<Group> Cube {
.
.
.
}
}
So, there should be a common group for all the objects for the animations to work well.