... aaaaaaaaaaaaaaand just as expected, 1pm server time, mission success rate back to 100%.
I'm not sure, because I'm asleep at that time, but somehow I have a feeling the switch back from less than 20% to 100% success happens around the same time when the new chest appears in the partner sites.
I was about to announce I've fix the bug.
It was a mater of wrong timer check, simple as that. ( < instead of <=, if you see what I mean XD ).
Mission success rate should be really better now.
I've also added the mission update; mission icon disappear if success, notification if not success.
Best!