Audio sound on stops from playing. Cubase 11 Only

Since the install of Cubase 11, it now has the annoying habit of playing the A1 key from my first and 2nd loaded VST instruments every time I stop play. These are in the first instance of Halion Sonic loaded in the VST Rack.

It doesn’t matter if I use my CC121 Controller, my PC keyboard spacebar, or the transport stop button.

It does not do this in Cubase Pro 10.5. I still have it installed.
I have downloaded the latest drivers for my CC121 and my UR-RT4.
Also updated my Halion Sonic as well.
If I mute the devices then the sound stops.
Any ideas?

I guess it’s a double post… More or less the same problem as on the other thread?