Version 1.0 64bits (Apr 29 2022)
I'm having an issue with Editing IPTC values, and it might be how it's intended to behave, but I think it feels like a bug - or some behaviour that has not been completely thought through.
Effect: IPTC Caption edits are lost - and not in an obvious way.
To reproduce:
1. Open Edit IPTC-IIM/XMP dialog and go to the Options tab
2. Under Multiple selections, confirm that Replace only if original value is empty is ticked, close the dialog
(*ASIDE: ... by pressing Cancel, and note that this does not undo any changes you might have just made as you might expect from a Cancel button)
3. Select 2 or more images in the browser window
4. Open the Edit IPTC-IIM/XMP dialog again
5. Make a change to the Caption text on the first image and use the arrow ">" button to move to the next image
6. Use the opposite arrow to return to the image you just edited and witness that the change you just made is gone
Why would I ever want to simply throw away, without warning, a change I just typed in? This behaviour is totally unexpected regardless of what box is ticked in the (hidden away) Options tab. I lost about 15 minutes of typing in detailed captions because of this.
It feels like a bug. 
Another reason why it feels like a bug: How am I supposed to edit an existing caption when going through multiple images? With this option unticked I simply cannot make a change. The only way I can do it is to select only one image. This can't be the way it's meant to be functioning surely? (It was not like this in releases from a few years ago.)
Also consider that on the Options tab it specifically says Multiple Selections. So I would expect that to come into play when I choose Write to All Files, not just moving between a single file.
In summary, expected behaviour: When editing text in the caption text box, changes should ALWAYS be saved when moving between images (or there should be a warning that this text is going to be discarded!)
Best regards,
Julie
Thanks to your detailed description I can reproduce