What is Maximum Deferral of Self-Employment Tax Payments line 18? I have a 0 in that line, but keep getting an error that says it's too large.

Line 18 states "Enter the portion of line 3 that can be attributed to March 27, 2020, through December 31, 2020".  Line 3 is a negative number (a loss).  I've tried several values and nothing seems to work.