Placing User-Defined Compound Wall as Arc

I have created a compound wall type and have successfully placed it as a straight wall.

However when I try to place it as an arc (edge or center) it disappears on the final click. The screengrab shows what I see before the final click.

The wall consists of two layers of blockwork separated by a cavity and finished each side with two layers of plasterboard with a timber skirting. I have tried with simpler compound walls (defined by me) but it still does not work. The wall types included in the Uniclass GB dataset that I am using place as I would expect.

I am using Bentley Architecture Select Series 1 08.11.07.87

Thanks,
Thomas