I have a user who do not able to see a related list of custom object, while her peers able. Here are few items to start look into:
- Check user Profile, if she has read permission to that object (child object). If not, go to user detail and check Permission Set assigned to that user if has read permission to that object.
- Check for any Record Type for the parent object, if yes, what is the record type for the particular parent record.
- Check Page Layout Assignment in the parent object and which page is assigned to that parent record
- Make sure in parent object Page Layout include child object as related list
If all checked and nothing wrong found, click Customize Page link in the parent object page layout when user login, make sure the child record is in Selected List. Sometimes user accidentally remove it and not remember. This is simple, but sometimes we just 'forget' as Salesforce is 'big'.
This page also accessible from User Name - My Settings - Display & Layout - Customize My Pages