The mouse cursor is hidden (invisible) inside the complete Nuendo window(s) if the track notepad in the inspector or MixConsole has focus.
The only workaround is to end editing with the ESC key.
I don’t know if it is intended to hide the mouse cursor completely as an indicator for disabled key commands, but I think it is very uncommon and confusing.
AFAIK it’s meant to be like that. When the cursor disappears it’s perhaps a little unexpected. I don’t really know why it was necessary to make it disappear from view.
I do not like that “feature” either.
Best regards
Yannick