In the latest snapshots, I can't add custom attributes to items. For example, if I type in the command: "/give @p wooden_sword{AttributeModifiers:[

{AttributeName:generic.armor,Amount:5,Operation:0,UUIDLeast:120632100,UUIDMost:99,Slot:mainhand,Name:generic.armor}

]}" I get a wooden sword that gives me + 5 defence when in the main hand.

However, if I type in this command in the latest snapshots, it doesn't work.
I have included images of it working on 1.15.2 and not working in 20w18a.

Edit: it is possible to transfer the items from version to version, the command does not work though.