I always have my Xcode assistant editor open with counterparts option. It's very handy to have an *.m file opened at standard editor while having corresponding *.h file in assistant editor.
After recent update to version 6.3 Xcode started to show random instead of corresponding headers quite often. Several clicks to "four squares" icon and mode usually brings it back (but it's very annoying).
Do you experience this too? How to fix it?
Note: deleting DerivedData didn't helped