Final Cut Pro X/ effect levels differ between preview and bounce

Does someone know what the reason could be for difference of effect levels between preview and bounce?!
I did cut one video file several times and added different effects like a simple tile and some stylize effects.
The effects are faded in and out which is visible in the preview,
though when I bounce the fades are not visible...

What effects exactly? How exactly are you fading the effect? Keyframes? What software version is this?

Thank you for the quick response!
I am using the Final Cut Pro Version 10.0.7
The language I use the program in is German, so I hope my effect translations are accurate:
In the beginning I use the fade in function from the compositing/opacity,
simultaneously the effect that is called "graphic" fading in the amount
and on top there is "Luma-Keyer: Luma Rolloff"
In the preview everything is visible,
in the bounce the colors are different
and the graphic effect is the only one you can see clearly
Later on I fade in the "Tile effect"
in the preview the fade is visible
in the bounce it´s an abrupt jump to the full effect level, no fade

This is an old bug. The fade function will not work for this though it appears to. You have to use keyframes to animate the effect.

Thank you very much!!!

Keyframes where the key
here is the result of my first Final Cut Pro Video:

Cheers,
Pablo