Skills won't strengthen!
I have had this problem in the past and now it is becoming more and more regular. I would try to strengthen a skill and pass it, but after the exercise the icon refuses to turn its signature gold. I had 4 strength bars out of 5 and only needed to pass the exercise once to max it.
For example, I have had to pass the time and date exercise about 4 times now, the same exercise again and again before it acknowledges that I've strengthen it to the maximum. It's really frustrating!