The correct formatting for the Visible property expression should use the logical OR operator to check multiple values, like this:
Variable == "order" OR Variable == "missing-info"
If you wrote the expression exactly as described, and the component still isn't visible during testing, it's highly likely that the value stored in the variable doesn't match the string "order" or "missing-info" in terms of case, spelling, or extra whitespace.
For a visibility expression to work, the evaluation must return a Boolean True for the component to appear. Therefore, ensure your variable's actual content exactly equals one of those values. I recommend adding a temporary step before your visibility condition to log the variable's value or pass it to an agent, so you can confirm the precise string you're comparing against, and also double-check that your expression correctly refers to the variable you're testing.