Any PM Preferences to add some IPTC / resolution (dpi) or other info on Ingest? your workflow doesnt use xmp sidecars at all? What are your iptc preferences in PM? To be able to be compatible with various image editing programs, since not all of them cater to a common standard, PM can write image metadata in a variety of ways, some of which are mutually exclusive. Upon ingest, and depending on your settings, PM can (if I remember correctly) automatically create basic xmp sidecars to go along with the photos. Which would be preferred in some workflows. I assume you just have a wrong settings for your intended workflow. Or it might be a bug of course, but I would check the preferences first. There is a lightning button, "snapshot", in the IPTC prefs pane having several suggested options for best compatibility with different other editing software filled in. Or see the manual and forums for more detailed explanation. I would check these first , even though it seems you already did, there are some options in other pref panes which might affect it as well, and ingest options too.
Hope this helps