I just noticed this clause on the lounge admittance page:
There is a similar clause for those who have been given an upgrade to Business Class. I'm pretty sure that this wasn't specifically called out previously. I had read on here people stating this to be true, but I didn't believe it!
It wasn't specifically called out, but that has been the practice for years. My wife received an op-up many years ago to J. She was CX GR. She asked for lounge invitation at the counter, and was specifically told that she didn't get lounge access.