Thanks Youlean.
But meanwhile I think it probably has nothing to do with your IPlug version as I now have this problem also on some older projects, so I think it's something on my side.
But if you (or anyone) could confirm it's working as it should with your version that can at least narrow the cause.
edit:
To not spam your thread I've a new one here:
http://forum.cockos.com/showthread.php?t=190011