"I thought you did not need to report self-employment income until it hit $400."

Even if they never got a 1099, it would be reported because they got taxable income.

"no SE taxes kick in until youre over the $400 mark"

Once you enter everything that applies, the amount that flowed into the Schedule SE then is evaluated: "if that is less than $400, stop; you don’t owe self-employment tax."

You won't know until you fill in everything.