When SMF Play Mode is set to "Auto Select" or "Internal" on the KIYOLA KF-20 and KF-25, the damper pedal effect recorded in the song may also be applied to notes played on the keyboard. This may cause notes to sustain or stop even when the damper pedal is not pressed.
To prevent this, set SMF Play Mode to "External". For details, refer to Optimizing settings when playing along with a song (SMF Play Mode) in the KF-20/KF-25 Owner's Manual.
Note: If SMF Play Mode is set to "External", Piano Designer effects will not be applied to the piano sound of the song being played back. The sound character may differ between keyboard playing and song playback.