frag not doing good

hi i got 3 bright green star polypse and one is not blooming when the light comes on, the other 2 are doing fine and the one thats not comming out was doing fine for like 2 months and it was growing but hasnt come out for 4 days. i checked my levels and everything is fine but ph is a little low but the other 2 are doing fine. i put the edge of it in a rock hole when i got it couse i had no glue to hold it down but now it grew out the other side of the hole do you think the hole that its in is killing it? only about 1/4 a inch in the hole?