This is the kind of gibberish in the online helps that drives me nuts. I've read it 10 times and I can't figure out what they are trying to say.
Is the control on the subform different that the subform control???
Does the enter event run or not? If it's a form "control", and not a control on the form, where the heck is the Form's On Enter in the properties?
Form.LostFocus event (Access) | Microsoft Learn