Some XML files not recognized as XML

I have a very weird problem:
Sometimes my XML files aren't recognized by IntelliJ as XML files. I can load them as XML files without problem, but they wont be formated as XML files when I edit them, which is slightly annoying. What is even more strange that there seems like I have done nothing wrong, since if I change the name of the file, it works fine. I don't think I'm using names that would be reserved, some example of the files I have:

Component_A1.xml - works fine
Component_A2.xml - works fine
Component_A3.xml - nope
Component_A4.xml - works fine

Is there anyone that have had similar problems? Or know what is causing this?

I hope that I have made my problem clear,
Thank you in advance!