Sitecore 8.1 Preview doesn’t match current site
With the release of sitecore 8.1 came a minor little config change, the resolve site configuration is now default false, previous version this was default set to true.
The settings is in 8.1 is set to default false
<setting name="Preview.ResolveSite" value="false" />
when set to false the preview site, will always be set to what is configured in the following setting
<setting name="Preview.DefaultSite" value="website" />
Change the setting to true and Sitecore will try to resolve the sites matching a site from <sites> section.