Kammala jumla mai zuwa: Allen ba zai iya kaiwa karshe ba a farkon rabin kakar wasa, ya yi rashin nasara a cikin duka shida na karshe wanda ya kai. A Gasar Cin Kofin Duniya da Shanghai Masters Allen ya yi rashin nasara a kan Shaun Murphy, a Turanci ya buɗe a kan Mark Selby kuma a Gasar Zakarun Zakarun ta yi rashin nasara ga Judd Trump. A Gasar Ingila, ya sha wahala daga Stephen Maguire. Allen ya yi kokarin sake lashe gasar Scottish Open a
2018 ya ƙare a wasan yanke shawara na wasan kusa da na karshe da Jack Lisowski. A Gasar Cin Kofin Duniya Allen ya daidaita rikodin yin karni 5 a wasan zagaye na farko da Jamie Clarke; duk da haka, ya ci gaba da rasa wasan da Welsh mai lamba 89 - dan wasa mafi ƙarancin matsayi a gasar - 8-10. Ya gama kakar inda ya gama na karshe, a matsayin mai lamba 5.