I tried this several times, but I still didn't get the achivement. I had a perfect streak of 168 days and (more importantly) I wanted to get the 04/2017 achivement for getting a perfect month.
I did reset the time to yesterday around 23:40.
All activity rings on my watch are more then filled, so normaly I should get the achivement.
Then I restarted the Apple Watch.
I moved, but strangly I did not get any more activity registered.
I waited till "midnight", and the grey 4/2017-achivement just disapears from my activity app on my iPhone. When I look at the achivements, it seems my perfect streak ended as well.
Is there anything I can do?