Depends on how you have your bashrc configured. It's not a bug but a configuration and a non-default one at that. Take for example the following from my bashrc.
The HISTCONTROL environment variable, specifically the value ignorespace, will ignore commands that start with a space. From the bash man page,
A colon-separated list of values controlling how commands are saved on the history list. If the list of values includes ignorespace, lines which begin with a space character are not saved in the history list. A value of ignoredups causes lines matching the previous history entry to not be saved. A value of ignoreboth is shorthand for ignorespace and ignoredups. A value of erasedups causes all previous lines matching the current line to be removed from the history list before that line is saved. Any value not in the above list is ignored. If HISTCONTROL is unset, or does not include a valid value, all lines read by the shell parser are saved on the history list, subject to the value of HISTIGNORE. The second and subsequent lines of a multi-line compound command are not tested, and are added to the history regardless of the value of HISTCONTROL.
It's definite that you're configuring HISTCONTROL=ignorespace somewhere in your bash configurations. See the man page for what files bash loads as configuration.