When XML first was supported, I made new projects with my default project settings. This made the XML import go nuts and give me all sorts of problems like you’re experiencing.
You know what? The problem was my settings. Don’t use ‘extracting reel numbers from EDL’ and all that. It will only confuse Resolve. It only does what you’re telling the software to do.
Try removing all sorts of things like that, and then have a go.
Go to the Conform page, Load XML, and let Resolve setup the project settings and import source media.
It might open a file browser for you to guide Resolve to the correct folder where the media is saved.
As for pre-conform, did the timeline in FCP have multi tracks? Was the video spread all over those tracks? Because then that’s the problem. Flatten the sequence to one track and export only this track to the EDL. The pre-conform should be no problem then.