In Lightning Experience, when a user hovers over a lookup field (for example, an Account), the hover card (mini page layout preview) only displays Opportunities and Cases as related lists.
The Mini Page Layout is available for objects that have a lookup or master-detail relationship. When a user hovers over a lookup field on a record, a hover card (also known as a mini layout preview) is displayed, showing key fields and related lists for the related record.
Regardless of which related lists are selected in the Mini Page Layout configuration, the hover card will only display:
Configuring additional related lists (for example, Leads, Contacts, or Custom Objects) in the Mini Page Layout and saving the configuration successfully will not cause those related lists to appear in the hover card.
Similarly, removing Opportunities or Cases from the Mini Page Layout configuration will not remove them from the hover card; they continue to appear by default.
This behavior applies to all lookup relationships in Lightning Experience, including Lead → Account, Contact → Account, Opportunity → Account, and others.
Real-World Example
A customer configured the Person Account Mini Page Layout with both Leads and Opportunities related lists selected, including sub-fields such as Campaign Name. When opening a Lead record and hovering over the Account lookup field that referenced a Person Account, the hover card preview displayed only the Opportunities related list. The Leads related list did not appear despite being correctly configured in the Mini Page Layout. This is working as designed (WAD).
Resources
Please upvote the following IdeaExchange request:
Show any related list on hover in Lightning
https://ideas.salesforce.com/s/idea/a0B8W00000GdfruUAB/show-any-related-list-on-hover-in-lightning
NA
005386881

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