XHA1 screen turns yellow with ND filters above 6000 k
 

Has anyone else noticed this. On my xha1 (not s) I tend to use manual white balance a lot to dial in numbers as required. If it's a bright day, and I decide to use the ND filters, I can only dial up to about 5900k, for white balance... After that, the screen goes yellow which is unusable. I have two xha1 cameras, and they both do this. Is it a bug?