I am becoming convinced that the black icon bug in older versions of howler is related to screen dpi. Only problem is, I've yet been able to prove it.
The only time I've been able to observe the black icon bug was when the dpi was set to something other than 72.
Supporting dpi other than 72 is becoming a priority. Historically, Windows had an unfortunate bug, that if you changed your DPI, it would sometimes delete your user account. That's a rather serious bug.
Actually, it renamed the account, but the effect was the same until you could get it sorted out.