I've recently had Acrobat DC installed so that I could use the collaborative cloud sharing features to simplify the collection of signatures for document approvals. I've been unable to share any document. The software does not allow me to sign in. I appear as signed in when I look at the help menu but when I try to share a document it asks me to sign in again. I click on "sign in" and no other prompts or windows open. It's like the button isn't working.