pecan weevil infestation can cause the shuck to remained firmly attached to the nut. However, in this case, there was no indication of weevil activity. Was this one nut just slow to open up or had something gone wrong inside the nut?
It took a little effort, but I could force the tightly held shuck off the fourth nut. The shell inside had not yet developed normal shell color and I found a paper thin remnant of a pecan kernel inside.
Back in August, the development of kernel inside the stick-tight nut stopped during the water stage and a normal kernel never developed. Without a developing seed inside the shell, ripening hormones are not produced in the fall and the shuck does not open.