It's been brought to my attention that node hierarchies are broken in the current SMD exporter. This error started in a recent update. I will be releasing a fix later today.
This bug now fixed in http://www.wallworm.net/index.php/topic,1221.0.html
I have a fix for this but there is another important problem we need to fix. It appears that our build programming is outputting the WW files in a format that is incompatible with Max 2012. As soon as we fix that, the update will be released.
TO clarify, even the current WW is broken in Max 2012. So if you are stuck in 2012, you should not download the latest WW until this bug is fixed. I hope to have it addressed today.
Now fixed in http://www.wallworm.net/index.php/topic,1221.0.html