The column customiser displays the fields based on the asset view that you are in. For example, in the All Assets View, only the fields common across all the asset types will be displayed. If a specific asset type is selected, the fields relevant to that type will also be displayed along with the common fields. For further information, please refer to the below article:
https://support.freshservice.com/support/solutions/articles/227664-customizing-columns-in-assets-list-page