Strictly speaking this is a bug in the plugin but it affects other plugins too - so a workaround has just been added in Ardour. Hopefully it'll be in the next release of Mixbus... Thanks for flagging it up!
Knowledge is knowing a tomato is a fruit...
Wisdom is knowing you don't put tomatoes in a fruit salad !!
Wisdom is knowing you don't put tomatoes in a fruit salad !!