Black frame during/behind transitions

Plenty of transitions I apply to clips will add a BLACK frame to my clip or behind my clip. Here is an example: I apply a lens flare to a connected clip. The connected clip is a Generator from Motion where I animate a graphic in (so it doesn’t fill the entire screen- it’s just one graphic and transparency) - the lens flare animates in and then at some point I can see a black frame behind my lens flare and my graphic. IN FACT I can see the black fade in so first I get black with like 20% opacity and so on. I get this problem with other transitions as well so that I always end up with a black frame at some point.

Any idea 1) what causes this 2) how to fix this? I just drag and drop the transition onto the beginning of my connected clip which will automatically turn it into it’s own story line of course. I have already tried converting a clip to a compound clip and then apply the transition onto the clip INSIDE the compound clip. At some point I got it to work but I wasn’t able to recreate this again WITHOUt the black frame.

Thank you very much

It's the way the transition is designed to work. You might be able to fix it Motion or build a similar one there or find a third party transition that works as you would like.

I've realized that this is the way SOME transitions work and I am kinda stuck. I've already found a solution for the lens flare for example. I've simply applied it to an adjustment layer and changed the blend mode to screen. Problem solved.

The interesting thing is the "Clothesline" transition though because I've managed to get it JUST RIGHT but I am not able to reproduce it so maybe anyone knows how.

I have got a compound clip with single JPG inside. I've applied the Clothesline transition to the beginning of the JPG INSIDE the compound clip. The transition gets played correctly without any black.

Now I've duplicated this compound clip - put another JPG in there, copied my transition to the beginning/head of the new JPG and deleted the previous one so that the compound clip starts with the JPG) but here I get a big black frame.

So I got it to work. I just don't know HOW and what it different. Maybe somebody knows.

Here I have recreated the problem. It works just fine on the first clip but on the second clip I get the black frame. I am pretty sure that I am doing something wrong and I just don't know how to tell FCPX "Just apply this transition to the clip and not to anything BEFORE it" or something like that. Please take a look at the file. I hope I can upload 23 MB on here.

There is no function for that in FCP. The transition has to be modified in Motion.

Dear Tom,

thank you very much for your reply. Did you take a look at the file I've uploaded? Like I've said I did the same thing TWICE. It works the way it should for the first time but not for the second time. So it clearly is possible in FCPX and I am not sure what is going on - why it works for the first time and not the second time if its both the same. Would you kindly take a look? Thank you.

I looked. It works that way because in the first shot there is nothing adjacent to the clip. After that there is so the transition includes with the underlying content. It's the way the transition is built. It needs to be modified in Motion.