This means they are working on it. Once they have a date, they will update the website.
For more information on that Tax Topic 152, you can click that link provided by the IRS. https://www.irs.gov/taxtopics/tc152
The below Turbo Tax FAQ will provide information as to why some refunds take long.
Why do some refunds take longer than others?
https://ttlc.intuit.com/replies/3302330