The P25 doesn't fit. I have tried it.
I have also tried it and is DOES fit.
I have used the ArcBody with P25,P45, and P45+ and with Aptus 22
What I did find out,by accident, a few years ago when my Phase rep showed up to demo
a P25 on my Arc was that,initially, it did not fit-the back would not lock onto the ArcBody
as if something was blocking.
Not being very patient I started pushing and pulling the area around the film 'gate' on the
camera and without too much difficulty,and a lot of surprise, a small metal frame popped off the
camera after which any digital back I used with the Arc would fit without a problem.
Unfortunately,the Arc is long since gone as is the pop out frame so I can provide any
reference images for you to see.
Mark