Export multiple files

When I go to File tab/Export/Multi and select whole file, it renders all selected files from the file group.

But there is also an option to render all regions. Is it supposed to render all regions from all selected files at once?
Every time I try this I get error message saying there are no regions in the selected files (even though there are), and the only option in marker selection dropdown menu is Generic marker.

Is this a bug or am I misunderstanding this function?

Thanks for the report. This is a bug indeed. Will be fixed in 9.0.20.