Arbortext 5.4 displays linebreaks from SGML

We recently migrated from 4.3.1 to 5.4. On 4.3.1, the editor did not acknowledge line breaks in the SGML, which is how an SGML editor is supposed to behave. On 5.4, however, line endings in the SGML are recognized and displayed on screen. This makes it very difficult for the authors to search on phrases.

Any ideas? Thank you.