I may have caused this. I switched the Update Channel from Beta to Stable, installed the upgrade, and then shifted back to Beta.
After installing SR-3, L4 downloaded the update again and inform me that an update was ready to install, but when I clicked "Install and Relaunch", I received an error message from the Installer which then refused to quit. Every time I launched L4, I received the An Update is ready to install message. Each time the Installer gave the same error message.
I finally went to Jackcav/Library/Application Support/Logos4/some random file name/Update Manager/Installers and deleted the disk image there. That stopped the endless attempts at installing an update.
Must have had a Senior Moment, as I forgot to gather logs.
If you need logs, I will attempt to create the loop again.
For now, I have left the Update Channel on Stable, which is contrary to my nature.