The collaboration sidebar cannot be used to comment on specific elements of which asset?

HubSpot’s collaboration sidebar supports asset-level comments on lists, but element-specific commenting is only available for selected assets. HubSpot identifies campaigns, workflows, and marketing emails as assets where comments can be attached to specific elements. Lists are included as a supported asset for the sidebar, but they are not included in the set of assets that support element-level comments. This distinction separates general collaboration from targeted feedback inside an editor.