the computer keyboard for playing notes some times does not work.
This was the topic about Ardour, right?
https://forum.renoise.com/t/linux-computer-keyboard-does-not-work-in-ardour/44280
Since you’re experiencing that it works “most of the time”, I guess it’s not the exact same error though…
Are you sure it’s not simply because you found yourself in the phrase editor?
When pressing keys there, they play the sample or keyzone (which can contain blank spots)