Item group limited view

Hi all,
I have a issue with adding more item group in omeka classic exhibit.
I have different number is item groups in different exhibits with 50 to 90 and when i try to add more error appears item group cannot be added.
I have installed Block Party plugin and activated and Exhibit Builder.
I found some php files responsible for that view and there is writen 50 items but it is not that what i need because as i said it is different number in different exhibits.
The last place to check will be the MySQL DB if there is something about this behavior.
Please share some expiriance with item groups per exhibit.