There's a bug. When you drag a gold miner (I don't know for other units) the whole game goes black and only cursor is seen) so I had to refresh browser.Edit: it's not just a specific unit. I tried it on a Paladin same went black.
Thanks for the bug report!
Any specific thing you did so I can reproduce it (I tried dragging those units and it was fine)...I'm using chrome browser.
I'm using brave browser. I don't think I've done anything specific. Just tried to drag a hero to place on the map.
the same thing happened to me after a while of playing. So it was working fine until the bug
Ill keep an eye open on what could cause it...