The minimum width for the value box in the perspective dropdown is 45px, so if you have a dropdown smaller than that, eventually after you select your new value, it will be too far to the left to be seen in the dropdown, even with text centered and what not.
Like so:
To fix it you can add the following to your themes/light/common/dropdown.css
, but I thought I would put it here for anyone that needs it:
.ia_dropdown__valueSingle {
min-width: 15px !important;
}
Et Voilà!
NOTE: You dont have to do 15px, I just figured you wouldnt be going much smaller than that, but who knows thats probably why its 45px by default!