I’ve added two new IAP products with identical settings. One works fine for purchase, while the other returns an invalid error. What could be the reason?

I finished filling in business information and configuring Xcode, then created the first IAP product, which functioned properly the following day. I created the second product afterwards. After a three-day waiting period, it still triggers an invalid product error. Any newly created products I added afterward also show invalid product errors. All product details are completed and marked Ready to Submit, but I still cannot figure out what causes this problem.