I.e. the struct cannot be expanded and edited inline. The only way to edit it is to make modifications on the same struct somewhere else and copy/paste it around. This is obviously a suboptimal workflow.
EDIT: Actually, we can just open the thing up in the Property Matrix and there the struct is fully accessible again, but it would be neat if this additional step could be avoided.
Could you provide a little more information about this issue? What version of the Engine are you using (and are you using the Binary version, or did you build the Engine from source code)? Could you provide a few more details about how you are setting up the struct and trying to use it?
Thank you for the additional information that you provided. I was able to reproduce the issue that you have described, and I have entered a ticket about the issue to have it investigated further (UE-6815).