Scatter brush rotation orientation to line.
When using a scatter brush with rotation set to the line (not page) the vertical orientation will randomly flip. For instance, when I'm using the scatter brush to create a bush with stems and leaves pointing up (natural orientation), after creating the line and applying the scatter brush sometimes the brush will apply pointing down.
Please accept my sincere apology for the inconvenience. Please get in touch with us at any of the other support channels – https://helpx.adobe.com/support.html . Since this is not a generic issue that we can reproduce at our end, we will need someone to look into your machine to figure out what is going on here.
Also do try the steps provided by Herman.
Thanks & Regards,
Herman van Boeijen commented
This has to do with the path direction. If you flip your path direction, your brush will look like you intended again.
app.executeMenuCommand ('Reverse Path Direction');