@Menachem Shmei I don’t make it a habit of going to many Chabad houses nor Lubavitch shuls. I’ve been to maybe seven in my life. I know of one that has a picture of their Rebbe front and center. By simple logic it’s highly unlikely that this is the only one and I happen to have stumbled on to it.
There are people in authority in Chabad (you know their names) who have gone on record saying things like “Asking the (dead) Rebbe for help”, “The Rebbe is listening to our teffilos”, and “This is happening because the Rebbe wanted it”. You may be in denial that people literally daven to a man, but in the opinion of most of the Gedolim in Klal Yisroel, it absolutely happens and Chabad does nothing to discourage it. In fact, it’s encouraged with things like giving an invisible man an Aliya l’Torah, and telling people to ask bakoshois of a dead man at his kever.