IRS Rejected Return: Need Identity Protection PIN for Dependent Despite Never Requiring One Before - How to Proceed?

Filed my taxes and got rejected because apparently I need an Identity Protection PIN for my daughter. Never needed one before and checked the IRS website - it shows no PIN exists. I'm super confused because we've filed normally every other year without this issue. When I logged onto the IRS website, I saw a notification that says "You are eligible to enroll into the IP PIN Program." It explains that an Identity Protection PIN (IP PIN) is a six-digit number that prevents someone else from filing a tax return using your Social Security Number or Individual Taxpayer Identification Number. According to the site, "The IP PIN is known only to you and the IRS. It helps us verify your identity when you file your electronic or paper tax return. Even though you may not have a filing requirement, an IP PIN still protects your account." I also see that "An IP PIN is valid for one calendar year" and "New IP PINs are generated each year and can be retrieved or viewed by signing back into your online account starting in early January." It clearly states that "IP PIN must be used when filing any federal tax returns during the year including prior year returns." There's a section for "FAQs about the Identity Protection Personal Identification Number (IP PIN)" and an "Enroll in IP PIN" button at sa.www4.irs.gov Has anyone else suddenly needed an IP PIN for their dependent when they never needed one before? I don't understand why this is happening now when we've filed the same way for years with no issues. Do I need to enroll her in this program before I can file again?