When updating web / classic galleries the 'Update Web Gallery' never finishes. This occurs with all the templates in the 'Classic Gallery'. I can make changes to things like the Site Title, Collection Title, etc., in a Classic Gallery and those changes will be displayed on the monitor but images included in the gallery are never displayed. I can modify and create other gallery templates with no issue (Grid, Square, and Track) and images are shown appropriately. However, 'Preview In Browser' will work and reflect changes accordingly.
The Max 2021 Photography products updates have been released and include remedies for this topic.The updates will be rolling out worldwide, October 26 and 27, 2021. If you do not see the updates in your Creative Cloud Desktop app, you can refresh the apps to see if the updates are available in your region.The keyboard shortcut to refresh is [Cmd/Ctrl] + [Opt/Alt] + [ R ].
Note: iOS and Android updates may take up to a week to appear in your App Store.