Hospice Physician Won't Sign Official Death Certificate

Hey all. This is in Colorado. My grandmother passed away in September of 2024, and when we went to the funeral home to get arrangements made, we were provided with an unofficial document of her death certificate. On the physician signature, the physician had signed it along with stating her cause of death. I've been told by the funeral home in November that we had to wait 12 weeks for the death certificates, but there was no autopsy done, he stated natural causes/dementia which she did have, but now im finding out, (February 2025), he's refusing to sign the official document. The funeral home director has told him he needs to, but still refuses. She has said she will report him to the state and he told her to "go for it". I asked the corner why he refused, she basically said she didn't know why and the funeral home director said the same thing. She's left multiple calls for the hospice, and no returned calls and she said she wants me to call the hospice tomorrow and speak with the director. But im just curious on what I'm supposed to do if he still refuses and why he's refusing after he already stated her cause of death and his name is under the signature along with an address