EDIFACT uses sequences which have dfdl:initiatedContent="yes" but one or more of the child elements of the sequence is required, not optional.
Daffodil appears to execute a discriminator=true behavior even for these required elements, which means the point of uncertainty being discriminated is some enclosing one, as the element itself in the sequence doesn't have one.
The DFDL Spec clearly says that the initiatedContent only affects optional elements.
The right thing is for a required child to ignore initiatedContent.
If all children of a sequence are required and the sequence has initiatedContent, that should at least be a warning, because the initiatedContent property would then be entirely ignored. This case does come up in EDIFACT.