Can not add any new characters to my Yamato world

Hi, i added 2 new classes to my Yamato world yesterday and wanted to add new playable characters with those classes.

So I wanted to add a character named Aoi, prepared his character sheet and clicked submit. Aoi did not show up in the character list of the world afterwards and not in the location I asigned him to. So I repeated everything, added him again with preparing his character sheet because I thought I misclicked something.

And he again did not show up.

My world has atm 78 characters (because every custom race has 1 playable character of every class). Is it too much and I can not add any new ones?