These were added as extraObjectives for this quest; we do not yet have the capability to hide extraObjectives when their relevant primary Objective is completed. The only time extraObjectives get hidden is when the quest itself is marked complete.

That may all seem a bit verbose but the eventual point of me saying that is that this is not so much a bug, as much as a feature request. This could maybe be resolved at the same time as #4270, when we tie extraObjectives more closely to their root Objectives.

(see this comment for a bit more of an in-depth dive into the quirks of Objectives vs extraObjectives)

Should be fixed