I’m having the same issue, but found a workaround that does it for me:
Starting the game with C:\Program Files (x86)\Heroes of the Storm\Support64\HeroesSwitcher_x64.exe
Maybe it works for others too and perhaps it gives a clue about the nature and possible fixing of this annoying bug. (Sadly found it a little late, meant to buy Junkrat from my PC for my best buddy when he was at 50% off )