Yakuza Kiwami 2 (PC) final achievement (KIWAMI 2) not unlocking

Update: this is what I got after contacting the support again.
"I have just checked your account and confirmed no issues are detected that can cause this issue. Since this occurs with one achievement only on a specific game, this means the issue is within the game itself, and not the achievement system on our end, otherwise most if not none of the achievements of that game will unlock. This issue has to be reported to the game developers.

I’m truly sorry for this experience you faced. I don’t believe this can be sorted by you, as this is an in-game issue which can only be sorted by the game developers themselves. The game developer’s support page is https://support.sega.com/hc/en-us "

tl;dr for anyone who stumbles on this thread with the same problem: There is no answer, there is no solution, Microsoft can't help you, go contact the devs (it's pointless)

Yes, I saw the thread you've linked but it's for the Steam version that may work differently. And in that thread nobody seems to figure out the reason or a way to solve this problem, except for using SAM, which is basically a cheat software for unlocking steam achievements (which I really don't want to use and it will probably not work on GamePass version anyway).
I will try to contact the support. The reason I didn't do it in the first place is that at the time of me posting this question here, the "Contact us" page had a message that the support service is really busy at the moment and there was no "Contact us" button or even an "Ask a question" button for virtual agent.
Will update this post if I get any useful info from the support service.

Upd: this is what I got from the support assistant: "I just checked the case for you and i can confirm the achievements from our side for rest assured however for some achievements they can take up to 48h before they relfect in game automatically. You just need to allow ir some time please"

Will update the post again after 48h

Hi Syd_930, my name is Rodrigo. I'm an Independent Advisor and a member of the Microsoft community and I'd love to assist you today.

I am sorry to hear that.

This seems to be a bug, it has affected other players as well.

https://www.reddit.com/r/steamachievements/comments/rm4vd0/kiwami_2_achievement_bug/

Note: This is a non-Microsoft website. The page appears to be providing accurate, safe information. Watch out for ads on the site that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the site before you decide to download and install it.

I kindly ask you to speak with the XBOX Staff.

Please enter this link:

https://support.xbox.com/contact-us

They can check your information and verify what is happening.

Hi Syd, yes, I also don't recommend you use the SAM application, I only pointed out the topic to you due to this being the same problem.

It is possible to earn the achievement:

https://www.exophase.com/achievement/yakuza-kiwami-2-for-windows-10-xbox/207216-kiwami-2/

Note: This is a non-Microsoft website. The page appears to be providing accurate, safe information. Watch out for ads on the site that may advertise products frequently classified as a PUP (Potentially Unwanted Products). Thoroughly research any product advertised on the site before you decide to download and install it.

Hello, My name is Jesse. I'm an Independent Advisor and a member of the Microsoft community and I'd love to assist you today.

Yakuza 0, Yakuza Kiwami, and Yakuza Kiwami 2, will all leave the Xbox and PC versions of Game Pass on the 31st of December, 2022.

Hope this helps