Where did font-size go?

Today I am continuing to edit an Engage interaction. Now I suddenly notice that option to change the font size has disappeared.

If I look at the first screenshot in this page, it should be where the red arrow is.

I have noticed similar behaviour in Quizmaker, but that was always the result of the face that both form view and slide view seemed to be selected (this apparantly happens sometimes, when you set Quizmaker to open questions in Slide view by default).

Is there something similar going on in Engage?