If there is a choice field and set it as required in the Custom List, when using qListForm to create an item and created a custom Save action and enable Perform Validation, the form still saved for the item using the custom save even there is no value being specified for the required field.
TitleqListForm – Custom save with validation enabled fails to warn if required fields are empty
CauseProduct Defect. Defect ID TF00329264 logged.
Create a Form Component Behaviour "Invalid When" condition for the Choice field.
Waiting for fix in a future release of QuickApps for SharePoint