I exported a rough cut as a both a P Pro project and as a Final Cut Pro XML project. The rough cut used MPEG files that had sidecar XMP files. Those XMP sidecar files did not end up in the projects' "media" folders and therefore markers did not show up in P Pro (I haven't checked FCP yet).
When I do a "send," markers do show up in P Pro.
Is the failure to include XMP files (sidecars or embedded) during an export by design?
As a follow-up to this, I exported files with embedded marker XMP data and those files opened and displayed the markers. And I exported files in a CanonXF folder/file structure and those too did open with their markers displayed.
I also copied/pasted the MPEG files XMP files to the assets folder and the markers then did show up.
So...this appears to be an issue only with stand-alone video files with XMP sidecars.
-- Jeff
Thank you, Jeff, I have submitted a bug.