On a scorecard with the ''demo'' project, I see 93% in yellow, and hovering shows ''Measured value 93 of 100, OK value >= 100%, Critical Value <= 90%.
There was no unusual configuration of ''Passed Tests''.
If you DRILL DOWN into the Yellow Cell, you should see the reason -- the color represents the TREND.
On my Demo project, when drilling down, I see a ''tests executed over time'' cumulative chart with a Blue line showing the current ''tests executed'' value as it changes for the various days of data represented. On mine, the Blue line ends within the Yellow/Critical zone.
So, this must represent the CURRENT state -- for mine, even though there were 93% executed (OK), since my current state (today) is in the Critical zone, it displays Yellow.