I just opened an ID file with alternate layouts in ID CC. All the pages were there but, they were not layed out in the pages panel as alternate layouts; there was just one long list.
I selected a page and chose, "Create Alternate Layout", and the alternate columns in the Pages panel appeared. Command-Z deleted the last layout group just created.
Just thought you would like to know.
BTW, I wish it were possible to swap one page of an alternate layout with the first page of that alternate layout; unfortunately, that does not seem possible. It seems the first page must always remain the first page. This is my wish for the next update.