iMac 27" mid 2015 Big Sur 11.7.1 fails to find MacOS Software Update using System Settings Software Update

System Preferences indicates that a software update exists for macOS Big Sur 11.7.1. Selecting Software Update opens Software Update window showing 'Finding Update...' with progress indicator moving back and forth. However, no software update is ever returned.

From the App Store entry for macOS Big Sur, the 'Get' button is enabled. Selecting the 'Get' button opens the same Software Update window as the one that appears when selecting Software Update from the System Preferences window. It also fails to find a software update.

Is there another method to obtain the update from macOS Big Sur 11.7.1 to 11.7.10?