Two Property Price Register queries

I noticed a "sold" sign suddenly put up outside 68 Booterstown Avenue last August. As there had never been a 'For Sale' sign outside, I was surprised to see the 'sold' sign. The sale price has still not appeared on Property Price Register. Under what conditions can a vendor avoid putting a record of the sale price on that website?

My second query is this: 63 Booterstown Avenue appears as sold in 2015 on Propertypriceregisterireland.com. However, it does not appear as sold on the official Property Price Register.ie. Why is this? Furthermore, unless I'm misreading the date on the 1st result, it seems to have been sold before it came on the market: "63 Booterstown Ave, Blackrock, Co. Dublin, Ireland Sold for € 380,000 on 2015-08-10. First appeared on 2015-08-19" What's going on with that?

Thanks.

Chet T16

I think first appeared means when it came on the register.

bluezulu49

It's on the official property price register here --> https://www.propertypriceregister.ie/Website/npsra/PPR/npsra-ppr.nsf/eStampUNID/UNID-027670AFE15016C480257EA600477EC7?OpenDocument

It can be difficult to find properties as they are apparently input electronically for stamp duty purposes and the data is published as is by the register. Thus some properties have addresses contracted e.g. to Ave rather than Avenue and if you search for Avenue you will not find Ave.