Bioware released a small patch on 10th of May. You can see what Update 5.9a contains in the patch notes below.
Learn Everything About SWTOR Update 5.9 The Nathema Conspiracy
General
- Fixed an issue that caused the progress for certain Achievements to randomly reset after patch 5.9. Achievements that were previously affected by this have now been restored.
- The objective “Crafting: Invasion Force” no longer automatically completes when the player receives an Invasion Force item.
- Fixed an issue with completed Daily Conquest Objectives resetting when logging onto another character. Completed Daily Objectives can now only be completed once per day for each Legacy.
- The Gravestone should no longer be visible after completing The Nathema Conspiracy in solo-story mode.