You may notice that I have replied to a similar post that you had made however I will also put the information here to benefit other users.
The smart matches are generated when you make a change in your family tree and publish them to your website. The data will then be compared with over 25 million other family trees at MyHeritage . Due to the fact that this takes some time it will take 2-3 of days to collection of the data. Large family tree projects may take a week.
The smart matching technology is very dynamic. It happens that in this "intermediate period" webmasters make changes in their family trees and remove individual cards and even entire trees. The result is that you have received a message that you have a smart match, but that the data has been removed. The result is an empty smart match.
Also you may wish to know that within the Family tree Builder Software the SmartMatch alorithms work differently to the online fmaily site and the matches are presented later than that on the online fmaily site. The reason is due to a lag in processing Smart Matches.
When you type the information into your tree (In Family tree Builder) we check to see if there are matches "ad-hoc" or "on the fly". If there is a match, the green icon appears to indicate we've found a preliminary match. The actual matches usually take a few days to be processed (as in the online fmaily site) so if you go to check your matches right away you won't see any, but ideally you should get matches within 2-3 days, and with large trees 1000 persons, it may take 4-7 days.
I have always found the Smart Matching system great, but limited.
I can go along and start adding new records based on confirmed matches and then at some point the system decides that a newly added match that came from some other tree no longer matches at which point I can not longer add preceding generations from that match.
Also, it would seem obvious to me, that if I add someone and there are more generations available (certainly preceeding) then why doesn't the system simply give me the option of importing all the succeeding generations from the tree that gave me the match! Clearly if I make a definate match, then everything else should match also, so give the choice to just import it all. It would make this much easier to build out.
Finally I encounter numerous trees where the builders neglect to mark people dead that are clearly dead - born in the 1800's and before. It shouldn't be too difficult for the software to determine by place in the tree and surrounding information that someone is clearly dead. This is getting in the way of the smart matching merging algorythms. Esp adding superfolous records.