Just after the latest update, Steele leveled up to level 8 kineticist. Steel Will is no longer adding +5. In fact, per attached screen shot, Steele cannot level her Will as it is already at max for level 8. Note that she has all 13 points available to level yet Will is maxed. Attached save file is from just before resting after getting enough exp to level.
When the perk is earned, it also adds +5 to willpowerRaw. The perk's effect will add a bonus +5 to willpowerMax, so if the character was at max willpower before, they will continue to be maxed without needing to spend points.
This may be reverted after the team reviews before the next release, but I've updated the perk to not touch willpowerRaw (it will reduce willpowerRaw by 5 upon loading your game if you already have the perk), and instead will give bonus of 5 to the calculated willpower as well as willpowerMax (but this will now count towards the maximum raw limit to allow the leveling of willpowerRaw). I only do this because the perk is a static buff. If it was dynamic (like the value changes based on calculations or creating and removing), then this may be handled differently.
To make sure, I'll need a save file right before earning the perk, if possible. The save file you provided already has it earned and points spent, so there's little I am able to test with.
Again, this may be reverted if there's an issue, but hopefully it works as intended.