Welcome @bret354 to the community!
I am sorry to hear that the 31 steps you completed disappeared.
I am wondering if maybe the account was not accessed to complete the steps. (I have done this myself, with my Certification Projects and kicked myself hard after when it was too late to sign in and save the code, which is why I am asking this question).
If, like me, you have to do them again, at least we are getting more experience using the codes.
Were the steps all submitted for completion?
I am not sure why it would happen.
Was your Cat Photo App still showing completed?
Hopefully, it will be able to be solved for you.
On top of what @Gray.n.Grey said, I just want to remind you the practice projects are not required to claim certifications. So, do not feel like you have to repeat lessons if you do not want to.