If you click on the little stardock symbol in the top left and select "Register a Product" and then click on "Add Registration" at the bottom, you may then be able to get Entrenchment.
Are you using impulse? If so, simply click on My Games at the top and then double click on entrenchment.
No worries, glad it helped. I just hope they get it all sorted sooner rather than later.
It errors when you try and uninstall it i take it? If you go the directory where you installed it b right clicking on the icon for Sins and selecting "Open Application directory" you can manually delete it. You can then re-install the standard Sins. This worked for me. Hope it helps
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