That seems pretty strange. Your example doesn't involve any unusual fonts, such a variable fonts or SVG color fonts; Berlin Sans is just a regular "static" font. Intertwine seems to work alright with live text in my computer's copy of Illustrator (see attached image).
The first trouble-shooting step I'd try (if you haven't done this already) is reboot the computer, then re-launch Illustrator and try the Intertwine effect again. If that solution doesn't work try resetting Illustrator's Preferences file.