Just thought I'd drop this in here in case anyone else hadn't realised/wondered why it was happening.
When you get DNA done on Ancestry, you have the option to "search matches". This includes typing in, lets say, "Smith" and all your matches with anyone with surname Smith in their tree appear.
One of my tactics for finding relatives was doing this. Moreover, I found an area of someone's tree where I thought there would be likely connections. I contacted them and invited them to search for certain surnames in the tree to see if other cousins that I knew about matched up to them or not (as one of my DNA matches would be related to her if one suspect area of the tree was correct and another one would match if it was the second area of interest). She couldn't find either cousin through searching surnames. This might have suggested I'd got it wrong, but then I attempted to find her again using the search for surnames and couldn't find her even when using surnames I knew very well were in her tree.
Reply from Ancestry:
"Hi (Name), the feature is working properly, it can take up to 30 days after the results come in for matches to completely show in results. Are you or (her) new to DNA? The indexing behind the search functionality can take some time to populate matches and that is likely why that aspect of the matches section is taking longer, we apologise for any frustration that may be causing during this time."
