Here is a trick you can do. It achieves what you want.
Place another Column at the inside corner. Its size should be that portion of the Column that hangs into the room.
Do the SEO operation shown on the illustration.
Subtraction, but the important thing is to check the
Inherit Attributes of Operator radio button.
In 2D, select the small Column and move it to the back in Display Order so it does not cause problems in Floor Plan Display.
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