Lookup Filter Not Working in Salesforce Lightning Experience When Field Is Missing from Page Layout

To resolve lookup filter issues in Salesforce Lightning Experience, ensure that all fields referenced in the filter criteria are added to the relevant page layout. The steps differ depending on whether you are using a standard Lightning Record Page or a List View with inline editing.

To resolve this issue, ensure that the fields—especially standard fields—specified in the lookup filter criteria are added appropriately:

• For Lightning Record Pages: Add the required fields to the Page Layout associated with the Lightning Record Page. If the Record Detail component has been upgraded to Dynamic Forms, manually add these fields using the Lightning Record Page Editor.
• For List View Inline Editing: Ensure the required fields are included in the 'Select Fields to Display' settings.