Do you mean before last August? I didn't notice any problems between getting my DNA results in May and writing the Masterclass 3 months later.
Yes, I got my results in June last year, & I noticed fairly early on that searches weren't always finding matches I expected to show up in the list of results. I suspect this may have been mainly down to the limitations of this search, though sometimes it seemed like something else might be amiss.
One of the issues I have with searching DNA matches is that restricting the search by adding a place name is very much hit and miss. With uncommon surnames I don't add a location and the resulting list of matches is usually either very short or non-existent. However, searching for a more common surname without a location can produce an unmanageably long list of results to go through.
The location search, however, only searches on birth place and so relies on DNA cousins having (a) entered a birth place, and (b) entered it in Ancestry's standardised format. Thus adding a location to the search (however broadly defined) means that many genuine matches will not show up in the list of results, and I not uncommonly find a lengthy list of results shrinks to no results at all.
So I wholly support your method of searching matches, and anyone trying to work through tens of thousand of matches one by one is likely to end up feeling overwhelmed and disillusioned. But I think it is also worthwhile looking at individuals and checking for shared matches as well as looking through available trees, as this may pick up things a search has missed. I do this as a matter of course with all new matches, and have also done it for all matches where the confidence is rated good and above.