Along with iOS 12, there was a bunch of updates released on MacOS today, including new versions of Pages/Numbers/Keynote.
I just opened up a Pages document with a mixture of Hebrew and English in it, and I’ve noticed that the button to change the text direction has disappeared! It used to be in the ‘Alignment’ section of the text formatting ‘pane’.
This is very frustrating, and a bit strange since 7.1 specifically said it had ‘Improved support for Arabic and Hebrew.’.
Does anyone know where the text direction switch has gone to?
Check to see that your Hebrew keyboard is still installed, per the instructions provided by @bowline. If there are no right-to-left keyboards installed, the reverse direction button will not appear in Pages.