White = XYZ 33.06 35.81 31.06
The brightness is really low. That would explain why the instrument is having a hard time measuring the patches imho (did you read Frédéric's post regarding the matter, he already gave some very good pointers). Is there a way you can increase the brightness, maybe choose another/native whitepoint and/or position the instrument in another way like Frédéric suggested?
Regards, Florian