Xbox CTO Scott Van Vliet Explains Phantom Achievements Bug Affecting Completion Percentages

Xbox users last week discovered phantom achievements appearing on their profiles, causing previously completed games to display incorrect completion percentages. Players who had unlocked all available achievements in certain older games found their completion statistics had dropped to 98% or lower.

Xbox CTO Scott Van Vliet took to social media to explain the root cause. "A service change accidentally included legacy challenges in the total achievement count for some older games, which also affected the calculation of displayed completion percentages," Van Vliet wrote on September 19, 2026.

Van Vliet provided additional technical context about the issue. Legacy challenges were tracked as zero-gamerscore achievements under-the-hood for some older games, which created the confusion when they were inadvertently added to completion calculations. Despite the confusion, no underlying player data was actually affected by the bug.

The Xbox team moved quickly on remediation. "We've already rolled out a fix to the way completion percentages are displayed, and displayed total achievement counts will be fixed within the next few days. No need to update your clients to get them," Van Vliet said.

The CTO's direct communication about the issue reflects an ongoing trend of Xbox leadership providing transparent explanations for technical problems affecting the user experience. Van Vliet thanked players for their patience while the fixes were implemented.