i would add this weldment at the same time as the bottom two as a new group, no trim/extend.
now i add this weldment separately after I've done the bottom two and it shows up in my cut list as the correct size.
Thanks Glenn
Hi Ben
It seems to be the way SW trims the vertical body . It seems like SW does a sort of extrude up to next when creating the vertical body and this is causing your problem. I have never come across this before but I got the same problem when I recreated your part.
You can still create all the bodies in the one weldment feature by splitting the vertical line for the body that is causing your trouble and adding a dimension to match the size of angle you are using.
I'm guessing it's because when you were using the Trim/Extend function you chose Body instead of Surface for the Trimming Boundary. If you'll choose the narrow flat part at the edge of the angle instead then the vertical piece will terminate there.