Ultimatte 12

Hello, I am using BMD Ultimatte 12 4K in a blue screen studio. When using the Hold Matte function, a blue area will appear in the HM range of the PGM screen. How can I correct it?
https://forum.blackmagicdesign.com/
https://forum.blackmagicdesign.com/viewtopic.php?f=4&t=217811