@Roger_TL45Y@thorogoodchris1 I found a confirmation of your observation for Orobanche caryophyllacea: "gewoonlijk komt de gastheer niet tot bloei" (Weeda, E.J. et al., 1994. Nederlandse oecologische flora, deel 3, p. 241).
@Roger_TL45Y@thorogoodchris1 I agree. No evidence for Orobanche specifically inhibiting flowering of its host, only drainage of assimilates from host to parasite, of course.