Steps to Reproduce
Navigate to a Project Task record.
Note that the Project Tasks related list is the first related list on the form.
Right-click in the Project Task form header and select Configure > Form Layout from the context menu.
From the Selected fields slushbucket, remove the Phase type field.
Note:The field does not show on the form even though it is present because it is hidden by a UI Policy.
Save your changes and return to the form.
Note that the Project Tasks related list no longer displays on the form.
Use the Configure > Form Layout feature to add the Phase type field to the Project Task form.
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Related Problem: PRB706638