And the underlying fare bucket does not determine whether lounge access is granted.

The OP appears to continue to mistakenly assume that the fare bucket indicates the fare family; more specifically the OP appears to think that "O" means Business Light, and that "Z"/"J" indicate Business Standard or Business Flex.

This is incorrect. Each of the fare buckets used for Business Class can be associated with 2 or more of these Fare families.

You cannot state conclusively that an "O" fare excludes lounge access; "O" can be used to sell Business Light, Business Standard or Business Flex, so you need more information to determine whether lounge access is included.

You cannot state conclusively that a "Z" fare includes lounge access; "Z" can be used to sell Business Light, Business Standard or Business Flex, so you need more information to determine whether lounge access is included.

If the OP actually booked a Business Light fare, which first went on the market in late April, then there should have been no lounge access granted as part of the ticket; you don't even need to look at what fare bucket was used, because the fact it was sold as Business Light is what actually determines the conditions of the ticket.