It's grey currently, as those coins have staked now. But yesterday I had some that were literally almost 38 hours old before they staked. I'm waiting on some coins to stake in about 1.5 hours. They start staking right on schedule. I'm on Windows 7 64bit.
If it's not a lot of coins, the network weight is so high it will take a long time. As long as the green arrow comes on on schedule, that's important thing. How long it takes after that is anyones guess. Staking after the fourth day has always been difficult for everyone. There's just so much weight on the network, and so few blocks to be had in a single day. It's just impossible for everyone to stake. Even the larger holders struggle, and by the end, it's anyone's guess.
There are strategies to work around this, but none that come without significant risk.