I'm getting this strange behaviour when I sometimes click "stack" on a group. A new group is created inside the first one but it doesn't allow me to specify spacing, the field for that is not there. I click stack again, it creates yet another group inside the second one and so on ad infinitum but no stack spacing is ever available.
Thank you for reaching out. I have heard of this issue before. I assume a Repeat grid would be better for pattern making and defining spaces between objects than stacks. Stack is used for rearranging objects in relation to each other.