Remove .Date from DateTime.Now.Date and try this, it should work.

var todayChanges = kbEntities.Changelogs.Where(c => EntityFunctions.TruncateTime(c.creationdate) == EntityFunctions.TruncateTime(DateTime.Now) && (c.name == ChangelogBL.ChangeLogName.ChangedKB.ToString() || c.name == ChangelogBL.ChangeLogName.Imported.ToString())).ToList();