Topic describes it all. I had a successful trade with the same person earlier on a different account. I’ve seen it open a bugged trade screen, but now it won’t even tell me if the other accepted. Do I have to use a different login, or the same?
Hope this helps. 90% of the time, black screen occurs in trading when one of the traders type the name with the wrong case, like typing Steamtrainer instead of SteamTrainer. The rest of the time, it occurs either when the other person is online but hasn’t sent a trade request. If both of you are sure that you entered the other person’s tradename correctly, then try closing and re-opening the game and trade again. Else, it might be a matter not sending the trade requests at round the same time (somewhere around 10-20 seconds). Guide to online features in Pokemon Insurgence