IRS Sent Letter Saying No Record of My Filed Return Despite WMR Showing Accepted - What Should I Do?

Filed my taxes 3 weeks ago and WMR shows accepted but not approved. Nothing complicated on my return - just W2 income and standard deduction like last year. Starting to get worried since I need this money. I just received a letter from the IRS that is making me extremely confused. The letter states: "Information About the Request We Received On January 28, 2025, we received a request for verification of non-filing of a tax return. As of the date of this letter, we have no record of a processed tax return for the tax period listed above. If you have any questions, you can call 800-829-1040." How is this even possible? I definitely filed my taxes around February 1st, and the WMR tool even shows my return was accepted! But now they're sending me this letter saying they have no record of my return being processed? This doesn't make any sense. I've been waiting patiently for my refund since my return was very straightforward - literally just W2 income and the standard deduction exactly like I filed last year. Has anyone else received this kind of letter while WMR shows their return as accepted? I'm really starting to worry because I was counting on this money for some bills coming up. Should I call the number on the letter? File again? I don't understand how my return could be "accepted" but then I get a letter saying they have no record of me filing.