If I configure an action with SMS sending and set the "Default subject" and "Default message" for this action, SMS not sending, showing an error "Expected [OK] received []"

If set only the "Default message" and the "Default subject" field is empty, everything goes OK.

Read in the documentation, not mention about it. So either it should be patched to ignore "Default subject" when SMS is in action or the documentation should be updated about this nuance.