When I'm using a style and playing a song, it fairly often will misplay middle c. In other words it's the wrong tone. being as I'm really new and learning, for a while I thought I was just goofing and hitting the wrong key but as I got more comfortable with the song I decided that can't be. So I set up a camera and captured it and found I was hitting the right key so if I hit it and it sounds wrong, I could hit it again and it sounds right.
On the linked video, 35 seconds or so long, at the very end I hit the key and it tones wrong, and I quickly hit it again and it sounds right. Unfortunately, I hit it the second time every so briefly. The song is a beginners score of Lean on Me.
BTW...in this music it is bass clef in this instance, and it is configured for this song las the split point. Yamaha thought it might be a voice issue, and wanted me to try a different voice. It happened with the different voice also. Past couple days, instead of being off key, it has just not played anything...but I have to say I'm experimenting with how hard / soft I hit keys, and it may be my hitting it too soft. I need to play a bit more to determine that.