I guess it is maybe because of the live caption Chrome provides above on the right.
I tried to disinstall but I can’t. So I just turned it off but still LR button doesn’t show on the playback.
Then I tried on another Chrome account, it doesn’t have livecaption button and LR button is on the playback. 
I am having the same issue. It was working until few days ago. Possibly due to chrome website update. The button to turn on LR near where the volume button was is gone.
Same bug as being discussed here, for anyone looking for more details: Extension not displaying on specific YouTube accounts - #4 by emtilt
Same issue, in Canada
There was an issue recently on Youtube due to new anti-adblock protections, it should be resolved now. Please leave more details if you are still having a problem.
