Yes I have set it to transparent in the globals, and the tap tempo is set 'per preset' , instead of 'per snapshot'. What bothers me is the fact that the trail is controlled by the parameters of the disabled delay.
Let's say in snapshot 2 the delay is disabled, and the feedback is set to zero for snap2, then no audible trail will happen at all when switching to snap2. I'm not 100% sure but I think this behavior is new.