Is your hardware 100% compliant? This is related to another thread where I asked a recent question about "troubles arising from 'ineligible' hardware with Windows 11.
But it shouldn't matter in either case, except that the fix for this is to download the latest ISO or IMG file for Win 11 that is version 24H2 and do an "in-place-upgrade-repair" installation on your computer to "Save programs and files".
Just more inconvenient than having Windows Update manage it for you.
Look at your Update History to see if there had been an attempt to install 24H2 as a Feature Update that failed. Then, choose a course of action, such as that with my suggestion.