Consistent misses by 10U to left

In our league here in Canada, 10U is the first year of pitching. I am not an experienced coach but trying. Most of my My son’s mechanics look pretty good, he is balanced and moving straight towards the plate. His plant foot is landing on a line straight from the mound to home, with the foot slightly closed (about 30 degrees). However, he consistently misses about 6 inches to the left side of the plate - isn’t a batter fear thing. Happens with lefty batters too.

Any ideas?

Left handed or right handed?