I noticed this today when testing out Soothing Mist and Vivify.
Cast Renewing mist on yourself and another group member.
Cast Soothing Mist on yourself.
Cast Vivify on yourself.
Cast Vivify on yourself.
… The second one will break soothing mist and you will have a cast time.
Try the same thing except don’t Soothing Mist yourself, cast it on the other party member and you should be able to insta-cast Vivify more than once on them.
For what it’s worth it let me cast Enveloping Mist through the entire soothing mist and not break (on myself mode)… not that you’d want to do that.
My testing was using the Legion companion as group mate so perhaps that was the issue triggering this but someone might test this in beta and report if the same thing happens.
PS: I get the same behavior on Live.