Random black frames introduced with Fusion clip.

did a paint out of a clip in Fusion. Now there is a random black frame that blinks in the middle of the clip for no reason...
https://forum.blackmagicdesign.com/
https://forum.blackmagicdesign.com/viewtopic.php?f=21&t=73781
MediaOut1 failed at time 1023
Background1 cannot get DoD for Effect Mask at time 1023
PlanarTransform1 cannot get DoD for Input at time 1023
FilmGrain1 cannot get Parameter for Input at time 1023
FilmGrain1 cannot get Parameter for Input at time 1023
Merge1 cannot get foreground image at time 1023
MediaOut1 cannot get Parameter for Input at time 1023
Merge1 cannot get foreground image at time 1023