miter cut / corner releif of a chane flange bend

Hi, trying to understand how to get what I want.  While I have options, nothing seem to change when various option are chosen..

1) I made a chain flange to have a nice flange about the 2 sides of an 'L' shape.

It then makes the flange, and creates both a corner relief and a mitered cut.  If I choose "closed" I get a closed off corner, which is what I believe I want.  But it does give a bit of a weird shape on the flat pattern.

It also gives a gap.  The end of the gap isn't really 'tangent' to the inside of the corner bend radius, which I would have expected.

Now, if I have an open corner, the gap creates a little 'tooth' on each side of the mating mitered flange edges. (See mitered.jpg)  I then need to do an unbend / bend back with an extrusion cut to remove these "bits", and get a simple 45°cuts on the flat pattern.. (See miter 2 & miter 3.jpg..)

2) while I have options to vary the corner relief, nothing seems to change with options chosen.  So, no idea what these do or control.

I feel I am stuck with whatever Creo is programmed to spit out..

any help or direction to a better  / concise explanation on how / what these options control?

dunno really how else to explain it..