Hi Bander,
Since you’re using 480 app id, session search will actually find lobbies hosted by other games that are also using an app id of 480. It looks like warning you’re getting in your log is implying that one of sessions you found has set some data on lobby that UE4 doesn’t recognize. Looking at log, there are a lot of unrecognized keys, and it could be that lobbies from other games are filling up search results up to Max Results value before any lobbies from your own game are returned. Assuming this is case, best fix is to of course get a unique app id, but increasing Max Results may work as well.
Hope that helps!