When They Have to Do Their Work
It is nine o'clock, the assignment has been open on the laptop since four, and nothing has been written. You have asked three times. The third time did not go well.
Most homework standoffs are not laziness and they are not defiance. They are avoidance, and avoidance is what anxiety looks like when it has nowhere else to go. A kid who cannot start is usually a kid who is afraid of starting badly.
The posts here are about the difference between a motivation problem and a starting problem, and what changes when you stop managing the work and start managing the dread around it.