Just an update to this. In the last two eVolve versions (or revit versions.. not sure what's creating the problem) I've noticed that when you try to connect different services, it will extend out a piece of the wrong service. Like you tie a vent down to a waste tapped tee and then it extends some waste pipe up a ways and adds a coupling to the vent pipe for some reason... it sucks. So I've noticed that I have way better results if I just take a vent no hub coupling and place it on the last waste fitting and then pipe from there. the mixed service is at the coupling and not the pipe so it doesn't do anything wonky and seems to hold better without issues. Just thought I'd throw that out there.