Completed 2c5 at 12'01 and after meeting up again a few days later all four of us noticed the time was no longer on our lists. We were all on Lumires at the time on 11/28/17.
List of times without the 12'01
After collecting all 7 items shown here I was surprised that the achievement did not display on-screen. I left it a day or so just in case it updated into the achievement-list still but it has not.
I asked @Matt & @Ryan to check the logs for me with the dates/times I gave. They are below...