When using a selector with name=, if there is a mob with a custom name or username with a space or symbol in it, the player/mob is not able to be found by the selector.

(Note on players with spaces in username - yes there are players with spaces in their names, it is possible - i.e. [space]Bob, or a space before the username)

Test:
1.Summon entity with CustomName with a space/symbol in it.

/summon Pig ~ ~ ~ {CustomName:Bob Bob,CustomNameVisible:1}
/summon Pig ~ ~ ~ {CustomName:/,CustomNameVisible:1}

2.Use a selector on entity.

/tp @e[name=Bob Bob] ~ ~5 ~
/tp @e[name=/] ~ ~5 ~

3.Errors:
First command: '@e[name=Bob' is not a valid number – Thinks it is a coordinate value
Second command: The entity UUID provided is in an invalid format