This refers to the problem that the monitor song might be altered by the Dj. When that song then becomes the main song kbpm-dj should use the new correct data, otherwiose a wrong matching could occur. The problmem here is of course that the player can be anywhere so we might simply not have the proper data available.
It seems that it is not reread properly ?
cannot update by selecting 'Secptrum' without doing anything else ?