Eli Zaretskii <eliz@gnu.org> writes:

>> The problem is that the braille unicode character BRAILLE PATTERN BLANK (0x2800) doesn't display as
>> blank but appears as what looks like a different character. I have submitted a question to stackoverflow which
>> includes screen shots of what the code should look like in both terminal and in emacs. I am running on
>> macOS Mojave 10.14.
>
> Probably macOS specific: that character displays fine on MS-Windows.

On my GNU/Linux box with both GTK and Lucid builds, I see that the
blanked dots do show up, similar to what the OP shows in their linked
screenshot.  Interestingly, I *don't* see the blanked dots in the
completion window for C-x 8 RET braille TAB.