I am using LMMS 1.1.3. On the Sone Editor, the first "instrument" I have is called a "Bell Chord" and it is from Triple Oscillator. I copied this from a project downloaded from the Share platform.
I opened up the piano roll on bar 21, entered some notes and played the music. Then I closed the piano roll and played the music from the song editor. I don't know what I have clicked but suddenly the notes showing on bar 21 disappeared, so it is showing a block of light gray bar. I cannot open the piano roll anymore, but when I play the song editor and it reached bar 22 (yes, for some reason it is bar 22 now), the music is still played.
I don't know what is going on. Could someone help me to open the piano roll again? Thanks in advance!

Bar 22 has music in it.
I opened up the piano roll on bar 21, entered some notes and played the music. Then I closed the piano roll and played the music from the song editor. I don't know what I have clicked but suddenly the notes showing on bar 21 disappeared, so it is showing a block of light gray bar. I cannot open the piano roll anymore, but when I play the song editor and it reached bar 22 (yes, for some reason it is bar 22 now), the music is still played.
I don't know what is going on. Could someone help me to open the piano roll again? Thanks in advance!

Bar 22 has music in it.