I know it's a while since this was active, but I have been having this issue on and off. The most recent post (Jan17) confirmed what I am seeing. I had a .ARW file open in the raw persona, and I opened a second .ARW file in a new tab. I applied my edits - (considerable exposure and highlights changes) to the second .ARW and clicked 'Develop'. The .ARW file I was developing reverted to the original pre-adjustment settings, but the exposure and highlight changes were applied to the first .ARW file I had opened which was still in the Develop persona.
Not sure if it is relevant, but I am opening images in Affinity from the ACDSEE asset-management tool
What is frustrating is that exiting Affinity and restating it - everything worked fine.
Hope this helps