Changing the size of filleted box stand makes fillets disappear

Using Grasshopper I’ve made a stand out of a box and filleted the internal and external edge. It all looks fine until I change the size of the box, the frames change size ok but the fillets disappear.
Any help much appreciated.
System info (disappearing fillets).txt (4.7 KB)

Without the .gh, nobody can help.

M?Q square_autosave.gh (69.5 KB)
Yes of course, here it is.
Thanks.

Solved the problem by using Split Brep component to create the frame.
Attached a file in case anyone is interested.
I still don’t understand why the other method using offsetting edges to create
the same doesn’t work.

M?Q Box (better).gh (9.4 KB)