Typically, one of these fixes the issue:
Deleting ClientRegistry.blob
Restarting Steam
Logging in and out
Logging in and out on another computer, then logging in again
Sorry to say, might just have to sit out for a day and check back next day. This is a common issue with steam and we can't really do anything.
Unless someone smarter has a new workaround, might have to just wait it out.
Sorry, hopefully see you in game soon.