Interesting. Every time I've ever vouched a comment, it came alive. (Though the last one I vouched ended up dead again after enough people flagged it, oops. I hope that doesn't mean I lost my power. In my defense, it was flagged to death based on being AI [apparently], which I didn't pick up the signal on, nothing super terrible / controversial.)

You are probably shadowbanned from flagging and vouching, which is separate from a commenting and posting shadowban. A shadowbanned comment only requires one vouch to come alive. A comment that is dead because of excessive flags or moderator action may require more.