Apples says no problem with XDCAM?
What follows is not a solution just a way to understand what is happening under the bonnet.
Try this workflow:
Leave FCPX closed and out of the equation for the moment.
Copy BPAV folder to your HD
Eject any SD , SXS reader or camera.
Open the XDCAM Transfer app
Click the Add.. button
Navigate to the BPAV folder
Select the import location from Preferences
Select any clips you wish to ‘Import’
Hit Import.
XDCAM Transfer will rapidly ‘unwrap’ the movies and place them in the destination folder
Go to folder, open a clip in something like MpegStreamClip or QT
Hit cmd i
this will bring up an info window
note the clips attributes
Video Tracks:
XDCAM EX 1080i50 (35 Mb/s VBR), 1920 × 1080, 25 fps, 35.00 Mbps
Audio Tracks:
(lpcm), 768 kbps
Now open FCPX
select Import Media.
look carefully at the drives available to you.
If you copied the BPAV folder to the top level of a finder window that will appear in the ‘CAMERAS’ pane. This applies to any camera folder type such as BPAV for XDCAM, PRIVATE for AVCHD and even DCIM if you have some still images copied rom a camera.
If these are a pain you can hide them by creating a folder at the top level and drop them in that.
OK, back to Import Media
Locate your newly unwrapped XDCAM clip
Hit' Import Selected'
Now notice the dialog ‘create optimized media’ …according to Apple this should be greyed out, ‘because XDCAM works just fine’ but its not

OK lets see what happens if do select it and also copy to events folder?
Once imported the Background Tasks render spins from 0-100%. Ok so I have created an optimized clip, ProRes?
Drop the clip on the timeline ,
Lets check, go File - Project Properties…hit the little spanner far right, says ‘Render Format ProRes
hit Export…(aka Share’ what a stupid name),
select Master File, now watch the Background Render Tasks drop back to 0% and slowly crawls up to 100%. rendering yet again.
Your export will open by default in QT, hit cmd i and you will see its ProRes. Now thats when we get ProRes
Go to your Final Cut Events folder
Open your Event
Note you will have an ‘Original Media’ folder with copies of the XDCAM clips
However no ‘Transcoded Media’ folder with no ‘High Quality Media’ as would be the case for formats other than XDCAM.
which is why editing XDCAM is ‘not just fine’ its a pain.
No Optimized media of XDCAM can ever be created.
As far as I can see…unless anybody knows different.
BTW I know you can Import direct from the BPAV folder with the Sony PDZK-LT2 FCPX plugin..but still no real transcode to ProRes.
No XDCAM is not just fine, ProRes? yes I totally agree bring that into FCPX and sure it works so much faster.
If you want to work really fast, SDI or HDMI out into devices such as the Ninja or Samurai Blade, record as 4:2:2 ProRes
have fun