I'm trying to create some reuse blocks for a project, and I'm having problems. I've created 3 reuse blocks. If I use one of them in a project, everything seems OK. If I import a second, I get an error message when I update the PCB about "The number of components in the following group templates is inconsistent with the reuse group", and one of the components is in the wrong place (and not part of the block group). When I add the third, the components are just randomly added to the layout as if they're new components, and no group is created. 

Is this something I'm doing wrong?