Hi guys

I have an RG6PCMLTD which recently developed a single note fret buzz which is mainly noticeable when playing not plugged in. It just kinda sounds dead/buzzy.

Only happens when I hold down the D string, 5th fret, so I am assuming the 6th fret is where the buzz is, as if I hold down the not before and after, they are perfect.

Any idea how to stop it? Tried a minor truss rod adjustment which made no difference.

Thanks