If you select a product property for fanning via the storefront display, all possible variants with this product property are displayed in the storefront. If the product has other properties, these are determined by the system for the preselection and it should be possible in this case to determine the preselected non-expanded product property yourself.
Example:
A shirt is available in S, M, L, XL and in green and blue. If you fan out by size, S, M, L, XL are displayed in the storefront, but the pre-selected colour variant is blue, for example, and this cannot be changed.