Why does my data for Components and some selections in Custom Fields not populate?

[Carolyn White]

In my Data Source setting, 1) I have a custom field selected that does not populate and 2) neither does anything from the Components section. The Components section has the link icon which has a hover over message "Table for linking 'Issues' and 'Components'."  The ERD shows that Components are linked to the Issues table, however, Components do not populate within the Issues table nor as a separate table. How, then, do I get the Components data and why don't some of my custom fields not populate?