You cannot view more classic skins when clicking the plus icon in the Character Creator for any skin pack you own but works for Marketplace Pass skins that you don't own.

How to reproduce:

1. Go to the Classic Skins tab in the Character Creator
2. Click the plus icon on any skin pack
3. Observe the button doing nothing upon clicking

Observed results:

The Plus Button does nothing upon clicking.

Expected results:

You should be taken to the full list of skins within a skin pack upon being clicked.