Custom Feat no longer affecting ability scores.

I've created a custom feat for lycanthropy and it has a modification to set the strength to 15 unless its already higher. I used the Bonus, Ability Score, Strength modifier to get this to work. 

It worked fine for a few weeks, but now the ability score no longer seems to be affected, but all of the other feat effects are present. Can anyone offer any guidance on how this can be fixed.

Did you add any other items (especially homebrew) to that character sheet recently that also interact with strength in any way? It could be that new item, especially if it's homebrew, causing an overriding issue.