Жуткая ошибка в PowerShell 18898

PS C:\WINDOWS\system32> $s = "started at system time 2018-08-14T04:01:13"
PS C:\WINDOWS\system32> $s -match '\d{2}:\d{2}:\d{2}'
True
PS C:\WINDOWS\system32> $s -match '\d{4}-\d{2}-\d{2}'
False
PS C:\WINDOWS\system32> $PsVersionTable

Name                           Value
----                           -----
PSVersion                      5.1.18898.1000
PSEdition                      Desktop
PSCompatibleVersions           {1.0, 2.0, 3.0, 4.0...}
BuildVersion                   10.0.18898.1000
CLRVersion                     4.0.30319.42000
WSManStackVersion              3.0
PSRemotingProtocolVersion      2.3
SerializationVersion           1.1.0.1