[SOLVED] Upgrades no longer applying discount for existing subscription

We have a site that was working fine for several months but is now not giving the upgrade discount (i.e. applying the remaining balance as a discount on the upgrade package).

Here's what we have:

YMA - this is just a 'container' /parent subscription

YMA-HS (parent is YMA)
YMA-MS (parent is YMA)
YMA-HSMS (parent is YMA)

The users usually purchase a YMA-HS or YMA-MS first and then at some point upgrade to YMA-HSMS. They should be allowed to have only one subscription active at a time within the YMA category. (There is another completely different/independent, non YMA, category with another individual subscription that is not effected by this one).

When they upgrade to YMA-HSMS any remaining subscription amount should be discounted off the full price of YMA-HSMS.
Using conditions, anyone who has YMA-HSMS doesn't see the YMA-HS or YMA-MS.

This was working but now is not.

The upgrade is there (when I have YMA-HS it shows YMA-HSMS as an upgrade option); however, when I add it it just ADDs it to my subscriptions. It doesn't upgrade the YMA-HS to YMA-HSMS .. I just end up with both at full price.

These 'upgrade' settings are still a bit confusing to me (so many different options in CBSubs - great but overwhelming at times ).
Can you tell me where I should look (which setting) that may be causing the problem?

Are all 3 plans exclusive? The prorating will not work for non-exclusive plans. As you stated it was working and now suddenly isn't, what has changed?

That was it (I think I need to put a post-it note on my screen that says 'remember to make them EXCLUSIVE').

I'm still not sure HOW that got changed, but resetting those to exclusive made it work again.

THANKS!!!