Region Union update incorrectly

Hi, I’ve created a definition that will filter groups by object name,
then each group intersects itself to generate inner section,

it worked nicely the first time I assigned objects to this node,
but when I tried to alter the input curves the result went wrong,
seems like Region Union won’t update the Input data until I reassigned it
or until I clipped & pasted the drawings again.

Is there any way to fix this node so that it will sync automatically when I modify the drawing?

Thanks. (21.7 KB) RegionUnionProblem_GH6.3dm (73.5 KB)