neowin[.]net/news/microsoft-confirms-windows-11-kb5044284--kb5046617-cant-install-new-updates/
learn.microsoft[.]com/en-us/windows/release-health/status-windows-11-24H2#3469msgdesc
Really, the only reason to post this is that if anyone has a new Win11 24H2 install, and has a problem where December's updates won't install, Microsoft is aware of the issue, and will hopefully have a fix in the future.
Microsoft isn't really clear in acknowledging this recent bug. If Win11 was installed from a USB stick, and if those setup files included the October or November Patch Tuesday updates, then the December 2024 Patch Tuesday update may not install. They don't say how the October or November updates had to be added to the setup files, if they were included in the ISOs that Microsoft provided, if you had to use their media creation tool to create the USB stick, or if you had to check the box to have Win11 setup look for updates during installation. I assume whomever at Microsoft was anxious to get out of there for the holiday, writing as little as possible -- it's listed as "Mitigated", with a workaround saying Don't Do That. :(