Play with HER Sch C so it show a positive... then see if the credit kicks in.

A negative Sch C doesn't represent earned "income" as it isn't income; it's a loss.  Earned 'gross' isn't the same thing.

AND you could try the optional SE tax computation to see if it triggers the CTC - but I don't know if that's legit even if it does work.  Research would be necessary...