Selectors and scores don't work in the "CustomName" nbt tag of entities.

Steps to reproduce for selectors:

1. /summon minecraft:armor_stand ~ ~ ~ {CustomName:" {\"selector\":\"@p\"}

   ",CustomNameVisible:true}

1. Look at the entity's name, it will say "@p" instead of you own username (see attached screenshot with "@p" in it). In other words it takes @p literally instead of as a selector. It does however accept "selector" as a valid argument, try changing the word "selector" in the command to a random word like "cake" and it will fail, this is why I think it is a bug opposed to a missing feature.

Steps to reproduce for scores:

1. /scoreboard objectives add test dummy
2. /scoreboard players set @p test 100
3. /summon minecraft:armor_stand ~ ~ ~ {CustomName:"{\"score\":{\"name\":\"@p\",\"objective\":\"test\"}}",CustomNameVisible:1b}
4. Look at the entity's name, and it will be a blank tiny width name tag (see other attached screenshot), not literal text like the last. Again changing the word "score" to a random word will produce an error.