many many times for me already each time i or opponent promote a pawn the promoted piece is invisible
it's very annoying and i don't see how this can't be fixed as it is not a lag issue on my part
I have similar problem.
For me it is often really dificult to promote paw.
For me the pop up window with possible promotion potions pops up for a split second and then dissapears leaving a pawn at the end.
If I refresh the page my move has not played still and I can try again.
I have to be crazy quick to do a promotion. Often loosing a lot of time of my game trying to do this.