In LibreOffice Calc, how can I insert a carriage return in a merged cell?

Alt + Enter in theory works in MS Excel - not here
I want to type in an address, but need it to wrap without spacing

Because of some strangeness with different spreadsheet programs, I had to press Delete, then Ctrl+Enter at the end of each line.

And what is the content of your cell? Could you explain a bit more (or share a sample file with the offending cell)? Thanks.

-1- It’s of no meaning insofar whether or not the cell is merged.
-2- A hard linebreak is entered with Ctrl+Enter into a Calc Cell.

(Avoid merged cells.)