Hey there. When you enter The Nexus and go right, towards the Well, the first set of drones you encounter belong to The Nexus. A lot of players get this one, then continue into the Well and do two there. They either leave or continue to the final set and find they can't destroy it, and think something is wrong because no triumphs popped. But it is all fine. That is what I see on your account. You've got 1/3 on The Nexus and 2/3 on Well of Infinitude. That technically is all fine, you've done three Vex Sector terminals this week, just out of sync, and only need to wait until the reset of the 22nd of June. The Eclipsed Zone will once again be Asterion Abyss again meaning the scanner is for Vex Sectors. You can go left at the fork at the Nexus and find the missing 2/3 for Nexus, then head back to the fork and go into the Well to find the final one there. You'll then earn both triumphs in one go.