removing carriage returns

I’m attempting to use this plugin to contain a simple list with 3 columns.

Each time I review or publish the list, the carriage return in each column is removed, causing the first two items in each column to be combined into one line.

For example, this:

1)
2)
3)
4)

Suddenly looks like this:

1)2)
3)
4)

Is there a trick to doing this?