I'm also able to export it properly. I used 92 dpi - what are you using? Def give us a copy of the png where the font has a black background.
Your file is huge (approx around 31 x 31 inches) - is that right? As Brynn said, the zoom is low. It took me a while to figure out how to export (esp for stock sites).
Also your objects are outside of the bounding box, so depending on which tab you choose, it may be ignoring the font totally. ps, if you need a good quality export, instead of making the file big, you make the file the same size as what you want your end output to be, then up the export dpi, I usually do around 300, and the png looks as good as the svg.
Not sure any of this is your issue though. A screen print of your export options and also the output png would be helpful.