It looks like the editor crashes when the comp has >= 130 teams in one stage. I've tested the limit, when the comp has a stage with 126 teams - it works fine, when it has 132 teams - it crashes ¯\_(ツ)_/¯
I've solved this issue by adding rules for this competition to the file with my rules. I think this can be done to test continental and international rules before SI fixes this.
This is a strange bug and it appears only testing continental rules (maybe international as well idk). When I've tested national rules, I didn't get this bug.
This is because of Real Name Fix.