Since 2am EST on Friday (afaik) there have been problems with starting custom games, sowing chaos among inhousers and NGS players alike.
Upon match start, the lobby host will be kicked, and then the host will be swapped, and that host will be kicked, repeating until the lobby is empty and closes.
The usual troubleshooting like restarting clients or changing lobby host do not resolve the issue.
Anecdotally, standard draft seems to work slightly more often than tournament / regular draft but any mode can crash out.