When my son was young we used to turn his homework into games. If he finished spelling exercises for 5 words, for example, he could pick a word and I would have to act it out. Basically, break the homework into pieces and offer a reward or find something fun in it.
Another useful tool is setting homework by time instead of page. This works really well for kids who look at the homework and get anxious because they think it will take "hours." When you have permission from the teacher to use time limits, you get to tell the child, "no, it won't take hours, it will take 30 minutes. As long as you stay focused, once 30 minutes are up, I sign you out as done, even if there are exercises you haven't gotten to." It is a great way for children to learn to sit down and get started, and doing so they learn important work habits and get an accurate feel for how long homework takes.
Both my AS and NT kids have had trouble sitting down to do homework. By itself, it isn't much of an indicator. But figuring out what the roadblocks are and WHY the process is difficult can help.
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Mom to an amazing young adult AS son, plus an also amazing non-AS daughter. Most likely part of the "Broader Autism Phenotype" (some traits).