Thank you for replying!
I have tried what you suggested and it hasn't worked, I'm afraid.
I know this may sound really silly (I'm new to Tableau), but could it have something to do with each bar labels being words rather than numbers? I assume this since my top bar chart doesn't seem to have any problems and that is the only main difference I see between them.
Thanks for your time.
if you post your workbook in a twbx format I will look at it