There is a bug in Photos with switching between R+J (I have reported it to them).
If you switch between R and J inside Photos’ Edit, then the extension gets the wrong image (and it has no ability to pick a different one).
If you switch outside of Photos Edit, and then enter edit (and then enter the extension), it should work properly.
What you wrote sounded like you were actually doing that, but other parts of your message sounds a lot like the bug I reported.
–Nik