So after last update for InDesign, I've noticed that I have the RTL Document setup not appearing and I need to change pages binding to RTL. And of course I've always had it downloaded supporting Arabic.
You've not given any information about your system: Please tell us what operating system (exactly) you're running. Please tell us (exactly) what InDesign version you're using.
If you've just installed the latest InDesign version, it's often helpful to restore your InDesign preferences and caches. Here's how: