Text to 844-647 Fails to Respond in Any Way

I have tried for weeks to get a response from 844-647. Sending YES, HELP, STOP result in no response from the short code. Because I cannot get a response from the short code, I cannot enable text notifications for sensors that might tell me the garage door was left open.

I have tried to set up text notifications on three phones (t-mobile and verizon) and all of them experience the same lack of feedback/response from 844-647.

I reported this and have been told it is working but T-Mobile confirmed they can see my texts going through and nothing coming back from the short code. Further, the smartthings app shows an error that clearly indicated they are not getting my approval to send texts in spite of my numerous YES replies.