When creating a dynamic perspective making use of the 'Categorize' option, 'Instance ID' field is not a selectable option.
Instance ID is not available when creating a dynamic perspective. Perspectives are intended to group assets (E.g. by tags, accounts, etc.). Using ID in this manner would create a group per instance and is not the intended use.
As an alternative, the suggestion is to either make use of the 'EC2 Instance Hours report', or create a Flex Report.