I think it's doing that because the label bleeds into the light-colored bar.
I don't like when Tableau does this to me.
One option you have is to shrink the font size a notch so it doesn't bleed into the light bar. But that's just a hack. Tomorrow's data might have an even smaller black portion, and the same thing could still happen.
You could go into the text editor, select the contents and force the color to be white. I don't know how white would look if ever the mark were to fall on the green bar.
Or change the viz so that the label comes ABOVE all the bars, not in the bar.
I thought I had previously created an idea in the IDEAS forum for a font type that had a border. (So, black border on each character, white lettering) but I can't find it. I did come across this one though, which embodies the exact sentiment:
Vote it up.
Thanks guys looks like an inherent issue with Tableau then. Joe - I have voted it up.
I have always wanted a halo option in the text formatting for this very reason.
Halo. That's a good description! I keep wanting to call it zebra, but that's not accurate.
Halo. I like it.
Halo's are great for text formatting - just not on the current F1 cars. I'd hate to be driving one of those at high speed with a vertical bar constantly in your face. Similar to driving a road car with your windscreen wipers stuck in the upright position!