I was about to start editing a project. Thought let me update the FCPX before a project.

I opened the files and suddenly see that my files are blown by more than a stop. All highlights are blown. After shooting last month, I had imported sample files and they were fine. I had monitored while shooting as well. Suddenly, everything looks like an amateur exposure mistake. I always shoot in c-log (using a Canon C300) and the footage is fine when viewed in Canon XF Utility. Has anyone faced such a problem? Is FCP applying somekind of LUT or something?

It's not applying a LUT from your description. You should reapply the LUT in the Settings menu in the info inspector.

Thanks William!

I found that FCPx has an option to switch off the c-log conversion. And it worked.

I expose the c-log files a bit differently then everyone else. So it was a problem for me. Nevertheless, it is sorted out now.