How to check the status of an amended return

TurboTax told me not to e-file the amended return, but to mail it in, which I did on April 20, 2021.

 

As I look over https://sa.www4.irs.gov/icce-core/load/gettrans/pages/availableTranscripts.xhtml I can find no mention of my amended return in the Record of Account Transcript.  When should I expect it to be mentioned there?  Or is there some better way to check the status?