I would use midi monitor insert plugin and check where problem is - any data to instrument or is something muting instrument.
I had issues with Kontakt when I used it long ago - and daw sent stuff every start of transport that reset things - on every midi channel there were volume, pan etc.
Pan I set on Kontakt were gone. If any CC7 it will set volume etc. CC11 expression which in turn can affect volume.
Midi monitor will tell.
Some more ideas below…
And are the chase back stuff, done every start, picking up some things earlier on track depending on where you start transport?
There are settings for midi in Cubase on top part of inspector about volume which is off. Use mousewheel and step that up to 120 or so.
This just to figure out what happends - if sound comes back.
There is a setting Insert Reset Event after record - depending on instrument this can reset more than you want. It sends out note-off on every note on every midi channel and reset controllers too.
I had a Roland D50 as master keyboard a while, and that also had some strange stuff - when all keys were up it always sent all-notes-off. So a chord was down, and then lifted - and all-notes-off cutting reverb tails and other things. So I glued down top key with adhesive tape. Also a clue if having a new keyboard you don’t know fully yet - there may be things in midi data.