If the IRS said internally, "yes, we need to reissue this check" on May 9, I would expect to receive it in 4 weeks or less. You may have problems with the mailing address as suggested. You can also contact the IRS and trace the new check. https://www.irs.gov/faqs/irs-procedures/refund-inquiries/refund-inquiries-0
I'm curious though, did the IRS contact you out of the blue and say "we noticed you never cashed your 2017 refund."? That sounds very odd. The IRS never contacts people by phone, they only send letters. I wonder if this might be some kind of scam. Did you pay anything for the new check?
Or did you call the IRS when you realized you never got your 2017 check and you just worded the question wrong?
