Skills won't turn gold
For me, both "Present Tense 1" and "Clothes" skills won't turn gold, no matter how many time I click the "Strengthen Skill" button and do the exercise.
I'm still getting the experience for it, but it refuses to go gold. Is this a bug?
If you'll look in the forum, "Present Tense 1" not re-gilding is discussed every few days.
As KateVinee said, the recommended workaround is to repeat the lesson inside that skill rather than strengthening the skill.
It's possible that the same is true for "Clothes", though I haven't had a problem with that one myself.