Not sure how to classify the behaviour I’ve discovered.
It adds an object to the validation controller explicitly.
Try entering something except “A” into the first field - it will correctly display an error.
Then click “Validate” the error will be gone until the second field is valid.
This happens because when an object is explicitly added to the controller all the rules are sequenced and if even one rule fails following sequence is not processed.
With an implicit flow validation works off bindings and each of them has its’ own sequence, so it does not matter if one field is invalid, other bindings are still processed.
Does it look like a bug ?