Hebrew’s missing vowels complicated how to pronounce a revived language.

Evidence

Jabotinsky was one of the champions of the revival of the Hebrew language, claiming, “A national culture, a pure national consciousness is depended upon the language in which a child receives his first impressions from the world that surrounds him.” This linguistic revival, however, raised a unique practical question of how to transform a language that was dead for centuries into a living tongue. This question was particularly difficult in the case of Hebrew, which has no natural vowels, thus bringing into question the proper pronunciation of this revived ancient tongue. — Ivan Davidson Kalmar, Derek Penslar, Orientalism and the Jews, 555