After update to 10.15.5 putting any app into fullscreen blanks out other external displays.

Hi,

I've got a new Mac mini 2018 with 3 x displays connected and after updating to 10.15.5 yesterday I've now got a problem.

When I try to put any app or video into full screen it works but it blanks the other 2 x displays. As soon as you exit full screen the other displays come back.

While you're in full screen mode and 2 screens are blank you can do Ctrl + Left / Right arrow to move out of full screen mode and all 3 screens move at the same time like they're one display.

Any idea how to fix this? Previously an app going full screen only affected the display it was running on.

Thanks!