My setup is this:

Joomla 2.5.24
CommunityBuilder 2.0.3
CB Conditional 4.0

I've set up the conditionals so that fields are shown/hidden properly in the registration form, and in the frontend and backend profile editor.

However, during the registration process, no data is recorded for any field that has a conditional applied to it.

Editing the profile in the frontend and backend works correctly; the conditional fields show/hide properly, and data can be edited and entered normally. In the registration form, the fields show/hide properly and data can be entered, but that data isn't recorded.

If I unpublish the CB conditional plugin, all the data in the fields is recorded properly; of course in that case all the fields show which isn't what I'm after.

No errors appearing in browser console or in error logs. The registration process works normally, except that the data for those conditional fields just doesn't get stored.

Any idea where I can start looking for the problem? I'd rather not have to hack my registration form and write the Javascript myself

Yes, it seems the fields I've input data for are losing their values on store.

First, I tried shutting off resetting in CB Conditional->Parameters, and that made no difference.

Could be I'm not quite understanding how to set up the conditions. When you say "only the last condition applied to a field is relevant", does that mean the conditions as they are numbered "1,2,3,etc." under the CB Conditional tab? Or as they are applied as you are using the form?

Here's what I've done. I have one main field with three options, and I want different additional fields to be shown depending on which option is selected:

Option 1 selected: show two additional fields
Option 2 selected: show one additional field
Option 3 selected: show no additional fields

I set two conditions on the Main field, that show/hide the additional fields when the main field value is equal to option 1 or option 2.

OK, I've tried a different setup: there are exactly four fields that should be shown/hidden based on the selection in the Main field. I have put one condition of type "Field conditional self" on each of those four optional fields. It's the same condition in each case: "If Main field is not equal to VALUE, hide this field".

Still the same problem :-/

UPDATE: Have tried again with just ONE field with one conditional on it. So it seems that the data from any field that has a conditional applied to it is not being saved.