Nonemergency hospital transfer with in network ambulance, why isn’t it all covered?

I’m in California. I went to the emergency room for an obstruction and they said they needed to move me to a different hospital. They wanted me to sign a release against medical advice form if I didn’t take an ambulance to get there. The ambulance I took was in network. My insurance plan says that it covers ambulance rides: Ambulance – Surface Ambulance “In Network – Covered in full Out of Network – Covered in full”

It also says “We Cover non-emergency ambulance transportation by a licensed ambulance service (either ground or air ambulance, as appropriate) between Facilities when the transport is any of the following:

From a non-participating Hospital to a participating Hospital;

To a Hospital that provides a higher level of care that was not available at the original Hospital;

To a more cost-effective Acute care Facility; or

From an Acute care Facility to a sub-Acute setting.”

From this, I thought that the ambulance would be covered, but my claim says that they are only paying about half of it and that I have to pay the rest.

The claim code section says “*00007 The amount is more than what your benefits cover, so you’ll have to pay the difference.”

Does anyone know why is this might be happening? I’m so confused.