External validation errors are not shown instantly

**I have the following setup:**
paper-form with paper-input elements. The errors property of the paper-input elements is set to model.validations.attrs.[field].messages. Validation is done with ember-cp-validations. This works fine so far with on exception: For one field the validation is done with the ds-error validator to validate error message from the server.

**This leads to the following problem:**
If I submit the form, the error message gets serialized correctly and even the paper-input method has the error property set BUT it is not shown, as the paper-input element is treated as untouched after submit. I have to first blur on the element to get the error message shown. I would expect this message to be visible instantly.