This is majorly annoying… I have updated to the latest, LibreOffice 6.0.6.2 and the layout has changed - I cannot find a way to insert a column! Did LibreOffice remove this option altogether? I have a text that I need to subdivide into 2 columns, how can I do it? Please advise.
Have you tried right clicking on the column or row header ?
Have you checked that you don’t have a row or column filter applied? This will prevent you from accessing the Add Column feature.
Insert a section for the 2 column text (select Insert>Section). Give the section a name you will recognise.
Format your new 2 column section (select Format>sections>Options>Columns)
Or are you thinking of inserting a column into a table (select Table>Insert>Columns Left/Right)?
THANK YOU! I meant if I had a paragraph of text that I wanted to subdivide into 2 columns on a page. Insert > Section works, but it’s counter intuitive. I wonder why LO decided to make this change. Anyway, my problem is solved. 
Thanks. The procedures give different results. Formatting a section gives “newspaper columns”, i.e. inserted text will automatically snake to fill one column and move on to the next. A table provides “parallel columns” as required, for example, when putting a text in one language alongside a paragraph by paragraph translation. But tables seem problematic when used to provide columns for a very long document.
The decision was reverted for 6.1.