Undead Nightmare 99% completion glitch?

[PankyA]

Hello everyone. As the title says, I got stuck at 99%. I have finished all the missions, saved all the missing people, completed all the challenges (except Tomahawk and Explosive rifle ones), found chupacabra and unicorn, unlocked all the outfits. So basically, I can’t get the “Zed's Dead, Baby” achievement, which is the last before the Platinum (playing on PS5). 

I have googled, the only similar topic I was able to find is - https://forum.psnprofiles.com/topic/149164-warning-undead-nightmare-is-still-glitched-in-the-new-ps4-port/?do=findComment&comment=2867854

 

But I don’t have a save before the final mission (completely forgot to do that). So I have a feeling that I have to finish the UN again, which is a bit frustrating. 

 

Has anyone experienced the same? 

Thanks for your input!