When booking over multiple nights, the rate first returned from the GDS is often an average, or simply the cost of the first night’s stay. The total is approximated based on this. i.e. the nightly rate is multiplied by the number of nights. Once that rate is actually selected, or full information is retrieved, the actual rate per night then becomes known. The rate that is first displayed at £85.00 may not actually turn out to be £85.00 per night, but £85.00 for the first night, £100.00 for the second and so on...
Therefore when the rate first loads, it may appear to be Within Policy, but once it is selected and we get the actual rate per night (not an approximate one) it may become Out of Policy. Rather than displaying a rate as Within Policy on the rates page and then Out of Policy on the summary page, the rate simply displays as Unknown.