The RMS visuals did have an offset bug in an early version of their release. This has now been rectified.
When the music is paused, the player stops calling the visual analyse function, and therefore the same data is passed to the draw function until analyse is called again. For some visuals this has the desired affect of retaining the last buffer of data, for others it appears not to make sense as no sound can be heard, but the display registers a sound input.
The player does flush the buffer on a pause, but stops passing this buffer to the visuals analyse function until playing is resumed. Little can be done about this, but the problem may be rectified in a future release of the player.