Replace Pages is no longer working in Adobe Acrobat

I just tried to replace a page in a PDF using Adobe Acrobat and it's not working.
It appears to carry out its function but then the change is not reflected in the actual PDF.
I have done this countless times before so I don't understand why this is happening now.
Additional details: I am working on MacOS Monterey and this is Adobe Acrobat Pro 2024.003.20121
I am trying to replace the second page with a JPEG image. I have done this several times before successfully.
