When using the Multi-line option for a text variable, this option is no longer present when the variable becomes an array. It is unsure if this is intended behavior or not. This issue does not appear to be a regression.
4.16.3 - CL: 3561208 - Issue present
4.17.1 - CL: 3586342 - Issue present
4.18 - CL: 3641171 - Issue present
Head over to the existingAnswerHub thread and let us know what's up.