Dynamic Component "Jumps" on Rescale

Help! I feel like i’ve got a handle on DC’s, but this simple one is confounding me. Trying to make a simple stud frame with plywood surround, which I can rescale. For some reason, this DC “jumps” to a new location when I move it, or when I scale it. It is very confusing. Any thoughts?
92523 Panel.skp (25.4 KB)

The parent axis should be center or on a corner, otherwise uneven scaling about axis

a quick fix is to match another added shell ( new parent) axis that isolates the internal old parent axis
Quick fix.skp (40.7 KB)

The new shell solved it. Thank you!!