that's been a long standing question for VST 32 v5.0. I't not covered in the manual and I've never seen a direct answer on any boards.
If I have to take some mutes out I usualy go to the place in the song where the mute comes on, enlarge, enlarge, enlarge...then scroll down to the automation track and use the scissors to cut out the mute line and glue the automation track back together again.
It's not perfect but it's a work around
Alec.