Text "Best Fit" is not working for Bitmap fonts?

Greetings,

for some reason Best Fit doesn't seem to be doing anything for my custom font. I want the font size to be adjusted dynamically based on the Rect Transform dimension of the Text. Checking Best Fit doesn't do it. If I change the font to use the default dynamic Arial font, it works fine, but we want to use bitmap fonts. So is that a bug or a limitation or something missing on my side?

Here's what my font looks like

Thanks