Sometimes you may notice that the gray capacity bar for a resource is smaller than for other resources, even though they have the same schedule.
This occurs because there is a card planned either in the past or in the future that exceeds the capacity of the resource. As a result, the gray mound is scaled back to visually represent the difference or ratio.
In this case, it's best to check what is planned for this resource and see if there is a high peak in capacity. Adjusting this will return the capacity bar to its normal display.
Note
It's also possible that the card exceeding the capacity is planned in a different period than the one you're filtering on.