Not quite the same; I can't even enter the store, but get a CTD when clicking the button. After the reinstall, I can't install my other expansions either :/
EDIT: The issue just... went away. Weird. I can now access store and DLC. Neat
This baffles me. Seen several posts reporting various issues much like yours and later an edit saying it started working by itself. Glad it is working, but I wish I could understand what the problem is to begin with. Thanks for reporting both the problem and that it got solved!