You can use ALT, H, FG to increase the font size (not as convenient for searching for a font size that works, but it's still there).
Also, typing ALT, H, then FF lets you type the font size you want.
Alternatively, you can add the font size up and down buttons to the quick access toolbar and type ALT, 4 or ALT, 5 (or whatever numbers they are on your toolbar) to increase and decrease the font. Again, not as convenient as CTL+> or CTL+< (which don't work for mine, either), but at least they're something. I thought there was a setting in Options that made it work, but I couldn't find it.