https://revisionfx.com/support/faqs/hostfaqs/sequences_longer/#Apple%20Final%20Cut%20Pro
“NOTE: We now suggest that you extend the clip by simply appending multiple copies of the original clip along the timeline in the intermediate sequence. This will create a new and different frame at each point in time. Now apply the Plugin to this intermediate extended sequence inside of another sequence. (We no longer suggest that you use the built in Noise video generator of FCP to extend a sequence).”
Turns out that they replaced these effects by FxPlugs plugins (the Motion thing). In doing so they not only created the problem you are having but as well it won’t create a unique frame at every frame anymore. Bug reported at Apple, useful when clients file bugs as well.
Pierre
RE:Vision Effects