its a bog plant not a tropical one so it can be persnickety about temp. Mine does fine in tanks without heaters but tends to melt/brown after awhile in tropical temps (76 and over)
if its new it could just be transitioning. i had some when redoing my tank it died off 90% or more. shed turned brown fell apart all i did was put it in a bowl for a few hours. i would give it some time.