It looks like if you use a font with a space in the name for a dynamic texture, such as Encode Sans, Android devices seem to accept it fine and load the correct font, but a Windows machine will fail to load and instead will use the default dynamic texture font.
Note, Encode Sans is a Google Font, I could not add it to the playground directly due to permissions. But once its in your cache its there until you clear it. So punch onto my development domain http://dern.tech and it should cache for your testing needs. Ill remove that link in a day or so once this bug gets logged, as not much to see ATM, I am just getting started on messing around with labels. Or, pick any other font with a space in the name.
document.fonts.ready seems to work! I found a (probably hacky ) way of adding a Google font to the playground, and I got the same results on Windows and Android However, you have to press play to load the font, since it’s added during the run.
Edit: Since the spacing on the name of the font was mentioned, I realized I probably should have tried with a font like that too. Again, have to press play for it to load, but it is displayed then: https://playground.babylonjs.com/#5ZCGRM#2042
) way of adding a Google font to the playground, and I got the same results on Windows and Android 
However, you have to press play to load the font, since it’s added during the run.
