If the Component is published as an embedded Component on a page using a static template, then this is correct. The Broker won't have anything for that Component in the ComponentPresentation table.
However, I wouldn't expect an entry in the ComponentPresentation table at all, but you seem to have a value of the boilerplate DD4T JSON, as you seem to indicate in your question. This implies the Component was published using a dynamic Component Template. Therefore, it is likely that there is an issue with your CT configuration.
Check that the proper DD4T Building Blocks are included in the CT. Also run the Component Template through Template Builder to help narrow down the cause.
LinkLevelparameter to the
Generate Dynamic PageTBB?