I also have a similar problem, but I noticed in fact that on my iPhone I just can't add any text replacement phrases. The list is blank, and whenever I try to add one nothing happens, and it stays blank.
Do you have a similar problem? I don't know if it's a general iOS big or just my device. Worked fine before iOS 9 final.
On my iPad no such problem.
In addition it seems Text Replacement is the single setting not searchable in the settings search bar (?!!)