Hey, everybody!
Maybe my way out of the situation will help someone.
When opening a csv. file in an external program, I noticed that there are unprintable characters in it. Some functions write them and you do not see them, but they still get into the csv. In my case it was the CHAR(10) function. It left invisible characters and I could not import the csv file into QB, it showed the message “Invoice No. missing in one of the rows.”.
It doesn't matter where these characters are, they can be anywhere and prevent you from working productively. 
Look screenshot.
Thank you.