Hi,
Unfortunately, this a known issue, and I can't say when/if it might be fixed.
What you could do to work around it (I've done this in my own projects), is render out the first 15-20 seconds of "FREEZE" audio, and then loop it with a long crossfade. It takes a bit of time for the stereo image to start narrowing, and this way you can get a "frozen" sound indefinitely. Not ideal, but it works.
-Tom
