AV video Fader behaviour

Is this supposed to happen?

 I have a cue stack providing a slide show with associated lighting changes. There are cues in it with no image to create intentional gaps.

In these gaps I can insert some video toy effects from playback memories.

If I fade up one of these the toy comes up as expected.

Leaving the fader up I then press GO and the toy effect crossfades to the cue stack’s next ‘slide’. 

So far so good. I assume the cue stack has taken over control and I can fade the toy PB out. However when I pull the playback fader down the slide from the cue stack fades out

If I then press GO with the PB fader down normal cue stack service is resumed.

If I don’t pull the fader down I can continue with the cue stack slide show until I do. The toy effect doesn’t reappear and it’s fader controls the video brightness of the cue stack images. 

If there is a slide up from the cue stack when I raise the toy playback nothing happens.  

Things get even more interesting if I have one toy on a playback and start to fade up another!