SSAS Bug: EXCEPT with nested FILTER functions on MEMBERVALUE

Last week while spending some time on the forums, I stumbled upon a thread where the user had presented 2 queries with seemingly identical logic but produced very different results. After a bit of troubleshooting I was stumped and fired off an S.O.S. tweet with the #ssashelp hashtag. Within the hour I had received a response from Chris Webb (b | t) who was able to reproduce the issue and agreed that it was a bug. Per Chris' recommendation, I opened a connect item. In the meantime, Chris was able to work the side-channels and receive a workaround from one of his "contacts".