Please run the following experiment and confirm my results.
1. Create a box, 5" x 3" x 2"
2. Convert to sheet metal, thickness 14 gauge
3. Edit convert-solid feature and select reverse thickness
For me, when I do this, SW automatically changes the thickness to 2" with no way of editing this. On a part this small, 2" plate cannot be bent, so it creates errors and won't let the change go through. This is a very simple process, and from other experiments, it seems to me that any time convert-solid is used, it cannot be edited after the fact. The only way to change it would be to change the size of the box.
The same is true of the K-factor. If you intially set it to 0.5 and need to change to .3 afterwards, it cannot do that.