Recently, Azure Stream Analytics has introduced the concept of compatibility levels. This is a way of versioning the Azure Stream Analytics runtime behaviour. Major bug fixes or new query behaviour are introduced within a certain compatibility level. This ensures backwards compatibility for existing Stream Analytics jobs, while providing major updates to the platform. Other types of upgrades, such as performance improvements, happen automatically behind the scenes as they are transparent for the service consumers.
The default compatibility level is 1.0, which is the behaviour of the service at the time it GA’d. The 1.1 compatibility level contains several fixes, including this one I’ve raised a while ago. You can find an overview of the 1.1 changes here.
I’m a bit surprised that new Azure Stream Analytics jobs get automatically the old version (1.0) of the runtime assigned. I would expect that the latest version is promoted to be used.