Mac open file dialog - "search" function - does not show all matching files
Typing directly into a Finder window doesn't generate a 'search' as such;  there is no filter generated, it merely selects the first match to your typed string.

So, if your folder is sorted by anything other than Name, then it will find the first match, yet not necessarily the first alphabetically - in your case it should find the newest match.

Setting the sort to Name, the same string will find &amp; select the first match alphabetically - the others will be directly beneath it, unselected.