Andrew,

Hatches in uniform scaled blocks explode perfect among other entities, even a hatch pattern is scaled.
Hatches in non-uniform scaled blocks are exploded as not scaled.

One could scale the hatch boundaries non-uniform.
For solid hatches the pattern scale doesn't matter.
For patterned hatches the pattern scale and angle is more problematic.
But why not explode it as is, the pattern is transformed as expected for the non-uniform scaled block reference.

Or one doesn't transform the pattern at all but then the the non-uniform scaled block reference isn't displayed correctly.

Regards,
CVH