When i summon a Wither Skeleton with any NBT tag, it appears without sword

Good afternoon! I've tried several times to summon a Wither Skeleton with the /summon command through a command cube.

I want it to involve a specific vanilla loot, so I used the nbt DeathLootTable tag.

The NBT tag works perfectly, but the Wither Skeleton appears without a sword and barely deals combat damage (aside from the Witherm effect, of course).

I've tried using other tags to force the equipment into its hands, but it hasn't worked. I've also tried associating the nbt DeathLootTable tag with other creatures summoned through other command cubes activated in a chain, but the Wither Skeleton still doesn't have a sword.

It only appears armed if I completely omit the DeathLootTable tag from the entire chain.