Why does bash only sometimes read #-commented commands from history

On my Arch Linux machine (5.2.15), history navigation with the arrow keys sees commands in ~/.bash_history that start with the # character.

On my Mac OS machine (bash 3.2.57), history navigation with the arrow keys does not see commands in ~/.bash_history that start with the # character.

The history builtin has the same behaviour: it sees those commands on the Arch machine, but not on OS X. Running history -r doesn't cause the commented commands to show up, though I can see them in ~/.bash_history.

What causes this difference in behaviour and how can I configure bash on Mac OS to behave like it does on Arch Linux (so I see commented history entries)?

Both machines have very similar bash configuration:

Mac OS:

$ shopt -p | grep hist shopt -s cmdhist shopt -s histappend shopt -u histreedit shopt -u histverify shopt -u lithist $ echo $HISTCONTROL ignorespace 

Arch:

$ shopt | grep hist cmdhist on histappend on histreedit off histverify off lithist off $ echo $HISTCONTROL ignorespace