We can produce sidecar . xmp files for images, they include metadata but not adjustments. From the Phase One help pages..
Capture One can read and store metadata in the following four formats: Embedded EXIF, Embedded IPTC-IIM, Embedded XMP and .XMP Sidecar file – these four types of metadata will be automatically updated and read.
David, how "automatic" is writing metadata supposed to be?
I have the Auto Sync sidecar XMP prefs set to "Full Sync" and have checked Prefer Sidecar over Embedded. I then change the rating on a raw file and wait. The sidecar never seems to change. The sidecar only seems to be rewritten when I open the Metadata panel and choose Sync from the triangle.