I have this in my blacklist:

{
  "ItemList": [
    "flare",
    "generator.wind.scrap",
    "searchlight"
  ]
}​

first of all I don't think thats actually blacklist, or you typed/pasted it wrong. 2nd don't use it, it's bad, read other posts. Remove those items in your LootTables.json file

That's a copy paste from the blacklist.json file.

I am having the same problem.  I'm trying to blacklist a good amount of items.  I've tried a bunch of modifications to the json file, and nothing seems to work.  I tried using MagicLoot, CustomLoot, and one or two others to try and do the same, couldn't get it to work, ComponentBlocker is the only thing that has worked for me thus far, and even that plug-in is not fully functioning as it should.  Random items are still not getting blacklisted, but about 75% seem to be.  Is blacklisting these short.names all of a sudden broken after updates, or does anyone have any clue why none of these Blacklist type of configuations/plug-ins seem to be fully functioning ?  If someone can assist, I'd be more than willing to compensate you for your time. 

discordFan

first of all I don't think thats actually blacklist, or you typed/pasted it wrong. 2nd don't use it, it's bad, read other posts. Remove those items in your LootTables.json file

This is a portion of the Blacklist.json hosted under Data folder, it's created in a seperate location than the BetterLoot.json.