If you create a custom page based an a single event type, say File Read, you will get an event log table that is good for this event type. It will contain the expected and relevant columns, corresponding with the attributes that are available.

However, you can modify your filter so that the page now instead includes a totally different set of event types (for example with the help of a stored selection).

In my use case, I want to create a page that would show me all event which has a non-empty attribute value for the attribute "Message". But I could never make the column "Message" visible in the table since it isn't an attribute for the original event type (file read).