A service that simplifies device provisioning and setup for end users, enabling zero-touch deployment
Hoping you can provide some additional details to help here. When you say this, what do you mean exactly? Sounds like the device failed autopilot and allowed you onto the desktop and now you're trying to onboard to Intune via Settings app on the OS?
***" I then decided to register it the standard way in Entra,"
***
One thing off the top of my head this makes me think of is if you have "Device platform restrictions" which prevent "personal device enrollment". Even though it's a corporate device, by not enrolling via Autopilot, the device enrollment restriction is kicking in and preventing you from enrolling that device. Have you tried wiping the device completely and going through the Autopilot process again?