LibreOffice 5.2.3.2 (x64)
Ctrl+Enter does not work.
I am also missing the menu item ‘Manual Break’ from the ‘Insert’ in the menu.
In my version 5.2.3.3 that was moved to the Sheet menu. Sheet - Insert Page break - Column break and Row break.
Indeed it has. Thank you for your response.
If the answer solves your question please tick the 
.