Hello All,
I've had this problem for a while now.
I can have an original item. Let's say just a box made with rectangle tool.
Give it a thick outline (let's say 4.0) and then click "Object-Convert outline to Object".
I will then copy and paste the second image, then flip it horizontally and move it to overlap original image.
I then click the second image, hold shift and click first image to select them both.
When I click "WELD" they will weld but the first image turns completely black.
If I click the first image first, then "SHIFT" and the second image, the second image turns black.
What my goal is, is to have an object like this but welded.
I have tried "TRIM" "INERSECT" "SIMPLIFY" "FRONT MINUS BACK""BACK MINUS FRONT" "COMBINE"
Now what I'm working on is more detailed than this, but this is an explanation. I understand that by just moving the second object to overlap the first object without flipping it will weld. It only happens when I have an item that is flipped either horizontally or vertically.
The paths get inverted when you flip. You can see that after the weld does , the inner shape is still there, despite being filled with black. Go into node edit mode, select the inner subpaths and reverse direction. You will be good.