More information:
The GM1 file is truncated when a rectangle shape is chosen. This truncates on any O/S or install I try .
With a rounded corner PCB for example, the length of GM1 files is 109KB but when using the normal rectangle choice it is 370 Bytes which is basically nothing.
I am now fairly certain this is a bug but will keep testing, but something is truncating the file. This was apparently a previous bug as well as I found a bug report for it.