I suffered this for weeks and no, it´s not caused by addons, so don´t waste time reinstalling things nor the simulator. The official patching process is buggy or maybe synchronization to cloud is what is buggy.
The only way to escape I found was to unplug network cable while in the updates screen loop until a connection loss message is displayed. Then plug it again. Game will load normally after connection is restored. You don´t need to do anything else.
More details and screeshots here: Welcome to "checking for updates" simulator - #5 by geloxo
Cheers