Story achievement "The big one!" not unlocking

Ok I'm really cursed with these bugged story achievements and it's pissing me off.

So I don't know why, the story achievement "The big one!" didn't unlock despite the fact I didn't skip any section, just had a few retries.

I even redid the mission once with the subtle approach and once with the obvious approach and still no achievement.

There's no way I'm redoing the entire game again, please tell me there's a way to unlock it.

Btw, I also noticed that on the Rockstar Social Club, it says I unlocked the achievement but the heist mission doesn't appear on the checklist. Looks like there's a big sync issue somewhere.

Edit : ok so I deleted my local save and got a rollback, looks like it was indeed a sync issue, my save on the cloud is just before the heist, I'm doing a manual save right now and I'm doing the mission again, fingers crossed

Edit 2 : alright it worked, I unlocked the achievement this time, thank god. However it wouldn't sync my cloud save on my console so I had to do it on xCloud