Hello there, Thanks for the report. One-Person Wrecking Crew is not intended to autocomplete retroactively. The triumph requirement is to complete all encounters in any dungeon solo without leaving the activity. So if this was an older solo Prophecy clear being expected to count now, that would explain it. If this was a fresh full solo clear during Monument of Triumph and it still did not complete, that would sound worth a closer look. In that case, a screenshot of the triumph and confirmation that it was done in one uninterrupted run would be especially helpful.