I'm posting this here because the in-game bugs forums are closed. If a Dev wants to move this, please do so.
My character, Blossom Rose on Ultros (NA), completed the Sastasha dungeon several times, however due to a server crash during the first run, all further runs were done using bugged out map data which did not display all explorable points. As a result, while others in my group would obtain the achievement for walking the exact same places I did, I remained unable to receive it, and my map is still bugged out.
Another character, Kimiko Shinobu, a friend of mine, is suffering from the exact same issue.
I was able to explore and receive the achievements for countless other zones, and in fact went out of my way to map the entire world save two or three zones that I couldn't run past the ranged level 49 mobs for, so I know the entirety of my map isn't bugged. Just the Sastasha dungeon.
This was NOT resolved as of the last day of Phase 4, and I did not receive a response when I tried to bring this to attention. I was told by support to post it on the forums a day ago, but oops, can't yet.