In 1921, Einstein won the Nobel Prize. The citation reads:
“To Albert Einstein for his services to theoretical physics and especially for his discovery of the law of the photoelectric effect.”
To be sure, Einstein is being acknowledge for the “the law of the photoelectric effect”, in other words for his photoelectric equation, but not for the photon concept. This attitude would persist until 1923, when new experimental results would convert pretty much everyone to the existence of photons.