The biggest problem with this bug is that I reported it to Autodesk and got nothing in return.  Okay, maybe that isn't the biggest problem; the biggest problem is that it significantly limited what we could offer our customers in our new Fences 10 eKit.

In addition to updating Fences 7 eKit for AutoCAD Architecture by adjusting cut planes, material settings and improving style management, I wanted to offer a suite of fence styles created with Curtain Walls since some users feel this is a better solution than using Railing Styles.  I quickly produced twenty Curtain Wall Styles to match fences we already offer as Railing Styles and figured I could have a compete suite finished in a month.  As I worked on this suite, I had some periodic AutoCAD Architecture crashes which is not particularly unusual when I create new styles and experiment with Block attachments.  At some point I found that the Copy/Paste feature in ACA didn't work and I set about to investigate why my Curtain Wall fence Styles were causing the Copy/Paste feature to fail.

I am sharing this story in hopes that someone at Autodesk takes it seriously and addresses it soon.  I checked ACA 2011 and it has not been fixed.

When you are homing in on the cause of a bug, it often takes a lot of trial and error runs to isolate the source.  One of the more frustrating aspects of this bug is that it isn't exactly consistent so you might repeat exact steps and not observe the failure.  However, eventually I noticed a visual phenomenon that provided the indication when the failure would occur: all of my Attached Blocks would change to the color of Layer 0.  After that, the "CopyClip" command would fail.

The color change can occur from something as simple as Panning or it only after direct editing of the Curtain Wall Style.

In the illustration to the right I show that I tracked this bug down to how a Block is attached to the Curtain Wall components.  If the "Replace Graphics" checkbox is used, essentially replacing the component with the Block, everything works fine.

I reported this bug to Autodesk late enough in 2009 that it might not have been possible to get a fix into AutoCAD Architecture 2011 but since I have not heard word back, I get the feeling nothing will be done unless a loud enough stink is made about it.

It might also be noteworthy that I'm running the 64bit version of ACA 2009, 2010 and 2011 on Vista 64bit and have not been able to test on 32bit versions.  The Blocks were all basic shapes created from Mass Elements.  I have sent a sample file so they have it.