Richard - if it states 'No price recorded' then there is no price paid information on the currently available register. If it's been recently sold and the application to register the new owner is with us then the
Price Paid Data may have been updated but the service you are referring to won't be until the actual register itself is updated.
The Price Paid data, not register, is updated in roughly real time as it's our data. The data is then shared with 3rd party websites and the timescale between that sharing and their updating will be much longer and will vary
The register information will only update with the new owner information once the application has completed.
So if you are trying to work out whether someone has submitted an application to register the purchase then worth checking the Price Paid Data first to see if a recent purchase price appears.