The team is aware of and are investigating an issue with Third Sister's Special Mission.
There was an absence with tagging which will be corrected.
With this fix, it will make that mission a little more difficult but we will be monitoring this fix and will adjust as necessary.
When the fix goes out those of you who are currently using the proper mods and using the proper strategy to beat it, you should not see a difference in your attempts on the mission. The team will monitor the fix and make adjustments if necessary.