Why wasn't my amended return saved?

Did you follow the procedure to amend the 2018 tax return using the TurboTax online editions as shown in this TurboTax support FAQ - https://ttlc.intuit.com/community/amending/help/how-do-i-amend-my-turbotax-online-return/00/27577

If you have already printed and mailed the amended tax return, then downloaded the PDF of your 2018 tax return from the Tax Home website and the return is not shown in the PDF, use Print Center and request all forms and worksheets.

When you sign onto your online account and land on the Tax Home web page, scroll down and click on Add a state.  

This will take you back to the 2018 online tax return.

Click on Tax Tools on the left side of the online program screen.  Then click on Print Center.  Then click on Print, save or preview this year's return.  Choose the option Include government and TurboTax worksheets