It sounds like it might be a subscription issue with the phone. I have not Mitel experience unfortunately. I wonder if it is correctly subscribing to the hint as it shows zero watchers.
Do you have a *989999@app-dialvm hint? This assumes you have retained the default FC of *98 for VM.
I also don’t know if this thread would be helpful (for 5330) to you but I saw it in a quick Google search.