August 2021 update won't install

Hello, I am running OSMC on a Raspberry Pi 3B+ using the November 2020 version of OSMC with Confluence skin. I try to update to the August version announced, but when I open the add-ons menu and select My OSMC and click update, it tells me no updates are available. I have an active wireless connection and otherwise it seems to work as expected. Any suggestions?

made a clean install ? updating such an old image can create several problems…