Hello,
I have a problem with my IIQ files from my P40+ and Phase One 645DF in LR 3.3. At some of my pictures I have a vertical line in the middle of the image. You can see it at the attached screenshot. If I open the file in Capture One 6.0.1 I can't see this line.
It's an issue with the stitching algorithm used to assemble the sensor arrays in the Camera Raw/Lightroom pipeline. The engineers are still working to get all the kinks out...each camera has slightly different sensor arrays that require matching. However, since Adobe has not "officially" listed the P40+ and P65+, theres a chance your individual sensor will show that result.
Not much you can do at the moment...just wait for the engineers to fix things. It's hopeful (or at least I am) that this will be addressed in the next ACR/LR update and official support for the P40+ and P65+ will be added.
I can say that with my P65+ back, I sometimes see this artifact up in the upper right quadrant of really blue skies...and it's usually pretty small and not too hard to get rid of. The "official" support should eliminate this not unlike the now official support for the P45+ files.