Line 4a is clearly intended for rental income. The new IRS instructions saying to report other types of business income on this line are obviously a mistake. The answer isn't to blindly follow them in this case, and the IRS is incorrect that the business rule needs fixing, it's the typo in the instructions that needs fixing.
At some point months from now maybe the IRS will figure out that this instruction was incorrect, and not that, as the known issues say, "business rules" should be fixed to allow filing with numbers on 4a and 4b that really shouldn't be there.
In the meantime the right thing to do is to leave 4a and 4b blank just like in previous years. TurboTax should get that and let you proceed to e-file with that edit.
