I have Cases that are logged against Assets, and I see them under Products record page layout as well in Classic (see image below). It is standard system behavior, that the products record show cases related to Assets (standard relationship).
All looks nice in Classic but in the Lightning experience it only shows Assets related list.
What have I tried so far?
- I have looked at another question Related Lists are not working in Lightning page
- Salesforce knowledge article pertaining to similar problem
- Ensured that the Case related list is added to the concerned Product page layout
- Tried to add a "Related List - Single" component by editing the Product Lightning page editor but Cases don't appear in that option either.