I knew this bug for very long time, but I was not reporting as I was waiting the pagination to work properly in RTL mode (which, I guess is disabled for RTL right now). Recently though I hit the zoom related bug more often so I thought I will bring it into the record. To produce it, select a language with RTL direction then open a thread that has a lot of pages. Now zoom in the page and reset the zoom level to natural again. All the pagination links will disappear except the first and last ones.