The spathe on my anthruim will not unfold they just turn brown. This is my 3 rd one. I can't get it to turn into a flower. Have a water meter & has southern exposure & looks very healthy. I would love to have a flower.
Humidity is the likely missing link. Think tropical. They don't want soggy soil but increasing humidity may help open those flowers.
A tray of water and pebbles can be placed under the pot. You can also run a small room humidifier near the plant.