I had the same problem. Try this help I noted above (and am repasting below).... you have to go into the actual filing on the left side (if doing it web version) and delete from there then go reenter in the program:
Go to Print and download/view your current return. See if you can find the error (in my case there were two 1099-NECs for the same job, one being correct and the other the error one). Then you keep that open and you can go to Tools and from there you can delete a file. I deleted the incorrect file and bam. All done and submitted!
I think it converted a 1099-MISC from last year into a 1099-NEC but then didn't delete it and I couldn't edit or change it.
