Is it just me, or is sort by active worse on sh.itjust.works than on other instances? On sh.itjust.works, it gives posts (both local and federated) that are weeks old. If I do the same on lemmy.world, it gives much more relevant posts that are a few hours to around a day old. Maybe there are some server settings that could be tweaked?
This is a current bug that will be fixed in the next version I believe. Some instances periodically restart the instance to get this statistic repopulated
And to make matters annoying, restarting the service that causes the sorting bug can trigger some other bugs (federation errors iirc). So there isn’t a “right” answer until the real fix comes.