I am trying to do this as well. I have figured out how to hide fields using Workflows tab within each plan of CB Subs, but the empty tabs still show at registration.
I tried to search this issue and all I could find were 4+ year old topics explaining that CB Subs & CB Fields/Conditionals conflicted and this was something that would be added.
Thank you. I just found the other topic in the professional member support forum & will reply there.
If anyone else is trying to do this it sounds like it's not possible without using an auto action to add custom jquery. There is a feature request with no progress:
forge.joomlapolis.com/issues/5341