Freeze Framing from the wrong source

I have a project with multiple timelines in it. At the end of each I have created a freeze frame. When I create a new element and create a freeze at the end I get the wrong source.
It seems to cycle through the history of freezes I've made, not only from this session but all timelines in the project.
I've tried double clicking the clip I'm freezing and copying it. I know that instructions say it's simply Option+F but is there some other keystroke I'm missing?

Thank you

adam.holzman wrote: I have a project with multiple timelines in it. ...

What is that in FCPX? There's just one, and maybe, for compos, some lanes...
Can you apply a screenshot of the part which doesn't create a freeze?

And Welcome Adam to fcp.co