Hello Fredrick,
I'm not sure how to explain this, it was a bit complicated when I contacted the developers.
As I understand it there is a bug in the OS and this is the issue: "Unconsidered EXR data properties for array elements". What this exactly mean, I don't know.
Until there is a solution and a new HWD file is released, PLUS+1 GUIDE will give you a warning instead of an error you can't fix. With this workaround you can at least compile the project.
I hope this give you some idea what is going on.
Have a nice day.