In 4 decades of tax prep, I have *NEVER* entered FEIN's from F.1099 MISC, or the 'new' NEC's.

It is not required by the IRS nor is it submitted with the efiling.  The total income is reported on the correct form, no detail is needed or required.  The fact PS (and some other software) allows for that data entry is just a method to get to the total.  

Any notices from the IRS related to F 1099 MISC/NEC income issues is because:

1) The total income reported on the return is less than the total income reported to the IRS (like, maybe.... the client forgot to provide one ??? Or, one got lost in the mail? Or, the issuer sent one to the IRS but not to your client.  Especially since some clients think the only income they have to report is what is shown on the various F.1099's.

2) The F.1099 showed the income in the wrong box, or even on the wrong form (like rent instead of NEC) and that wasn't taken into consideration when preparing the returns