Cubase Pro 9.5.10, RME TotalMixFX

Hi All, Hope you can help? I’ve just installed the RME HDSP AIO sound card and updated Cubase Pro to 9.5.10 everything seems to work well until I want to monitor the TotalMixFX channels when I try to open the mixer for TotalMix Cubase freezes/sits in the background until I put the pointer back on Cubase the only way I can use the mixer is to move the Cubase over to one side of the screen and the RME mixer to the other then point on Cubase, The freeze and sit in background happens when ever I touch the pointer outside of a Cubase Project, in other words I cannot run anything else alongside Cubase without it going into the background, Any Ideas? Cheers