Bug ? Standard transitions on primary clip affect below layers

Hi everyone,
I've been using FCPX for years now and today I'm stuck with something that I think wasn't the case before:
When I add a fade transition (or any other transition) to a primary story clip, it affects the clip below with a strange black effect. It's like the clip disappear and reappear as soon the transition is over. I know there is other way to do what I want, but I'm sure it wasn't the case before. Am I the only one to experience this strange behavior?

If you right-click on the affected transition, you'll see an option to 'Fade to black'. Uncheck the option and you're good!

Edit:  It's a toggle, so select the checked option to turn it off.

Hi dmetz,
You're awesome!
Never saw this option before. Do you have any idea why it's now selected by default (either I press Ctr + T or drag and drop the transition).
Is there a way to change that?

Hi dmetz,
You're awesome! It worked.
But do you have any idea why it's now set by default when I do Ctr + T / drag and drop at the end of the primary clip?
Is there a way to change that?

It happens automatically if you apply the transition to the last clip in the primary storyline.

I normally don't do this (transitions come after the content cut for me), so it didn't cross my mind to check... I don't see any way to change this behavior.

I'd say the assumption is if you're fading out on the last clip of your timeline, you want it to go dark.

Glad to help!