I have recently encountered a similar thing with a NOID Phal given to me by someone who wanted to be rid of it! The newest leaf came out like a tube/tunnel but was splitting in some places as though it wanted to open flat out.
At first I just split it open all the way but that didn't look very good and had all these new cut edges that I thought could invite some sort of infection, so I then cut it right off at the base of the leaf and covered the cut with cinnamon. Another new plant was already growing out at the side so it should certainly survive and I'll just wait to see if it will ever bloom again. Sorry I didn't think to take a picture.
Shirley