The pack filter doesn't work and its design. According to EA its what they call an "inclusive filter" rather than an "exclusive filter". So it just shows you everything that contains content from for example base game and Get Together if you set the filter that way, instead of only base game and Get Together. Basically they don't want you to be able to exclude stuff because they want you to see content you don't have to nag you to buy it. So it basically works the same as if you don't use the filter, just with extra steps.
Every time someone posts it as a bug on AnswerHQ, which is monthly, Cincrit posts something along the lines of "Yes, I know its broken and stupid and yes, I have told them repeatedly and no, they won't change it"
EDIT Also I dont pay attention to Maxis Picks any more as there is hardly ever anything that interests me. For a while, the builds were highly useable and built with only a couple of packs. but that wasn't the case the last time I paid attention They had seemed to have gone back to being overstuffed with clutter and built to be looked at, not played.
If the Picks are usable again that would be great to hear
EDIT 2: Also the lack of likes is a problem the Gallery has always had. And its a problem I have no idea how to fix. Maybe a nag screen they way Nexus Mods does it? I try to remember to like something when I download it as if its worth downloading its worth a like, but I dont always remember. Also, why can you like your own stuff?