8606 Filed but I have no basis. Can I just ignore this when I have to do my RMD

For a few years in the 1990's I made some Nondeductible IRA contributions.  I completed the 8606 when I filed using Turbo Tax.  I do not have complete records for this.  I am guessing it might be a total of $10,000.  I understand I have already paid tax on these contributions, and I will be taxed again if I do not list my basis.  Will I be breaking any laws if I do not do this?  I took take my first RMD last year (2024) and when I was entering the 1099R part from my RMD Turbo Tax asked me if I had any nondeductible contributions.  Can I just answer no and move forward.  Or am I breaking the law?

 

Thank you for any advice.