Using "distance" as an @a, @p, or @e[type=player] argument will make the command unable to find players.

How to reproduce:

• Make sure you're the only entity in the world

  /kill @e[type=!player]

• Type in chat:

  /say @a

  this works and will find the player.

• Type in chat

  /say @a[distance=..5]

  this does not work and state no entities were found.

• Type in chat

  /say @e[distance=..5]

  this works and will find the player.

• Type in chat

  /say @e[type=player]

  this works and will find the player.

• Type in chat

  /say @e[type=player,distance=..5]

  this does not work and state no entities were found.

• Type in chat

  /say @s[type=player,distance=..5]

  this works and will find the player.