Why do you think it is missing? What did you enter that requires an 8606?
An 8606 is automatically created when:
1) You make a new non-deductible Traditional IRA contribution.
2) You take a distribution from a IRA that has a after-tax "basis".
3) You make a conversion of a retirement account to a Roth IRA
If none of those occurred, then the last filed 8606 remains in effect
There are some circumstances when a 8606 must be files for other reasons and might require filing a stand-alone 8606.
https://ttlc.intuit.com/questions/1899503-what-is-form-8606-nondeductible-iras-used-for
**Disclaimer: This post is for discussion purposes only and is NOT tax advice. The author takes no responsibility for the accuracy of any information in this post.**